[Haskell-cafe] Case-insensitive lexing with Alex
Any suggestions on how to implement case-insensitive lexing with Alex? Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Case-insensitive lexing with Alex
On Jan 28, 2008, at 2:44 PM, Geoffrey Mainland wrote: map toLower onto your input before you pass it to your lexer? Or do you only want keywords to be case-insensitive? Just keywords. You can have Array or array or aRrAy. -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] C# parser written in Haskell
Does anyone have a C# parser written in Haskell? Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Yampa / AFRPVectorSpace.hs
On Dec 17, 2007, at 4:30 PM, Peter Verswyvelen wrote: Maybe you could place Yampa in a Darcs depot? darcs get http://wagerlabs.com/yampa I think we should move it to Google Code, though. -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Expert systems
Is there an expert system implemented in Haskell, or a library perhaps? A CLIPS/RETE implementation? The main stumbling point, from my perspective, is how to implement a knowledge base and check whether patterns with a certain shape have been asserted. It's much easier to do this in a dynamically-typed language. Am I mistaken? Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Missing _environ
Dan, On Nov 9, 2007, at 12:58 AM, Dan Piponi wrote: Well that was the crucial fact I needed. 6.8.1 is now built. ghci doesn't work, it complains about an unknown symbol '_environ' in HSbase-3.0.0.0.o The installation process strips the binaries which strips away _environ. You need to either find the place where install-sh -s is invoked and remove -s or copy ghc from compiler/stage2 into your installation directory. I think this should work. Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Composing trading strategies (was: Should I step into a minefield? / Writing a trading studio in Haskell)
Greg, Can you post a couple of examples of what the trading strategies look like? Thanks, Joel On Nov 8, 2007, at 7:32 PM, Greg Fitzgerald wrote: The idea is that the user composes an 'openPosition' and 'closePosition' trading strategies from a combinator library and gives them to the trading platform. The user's trading strategies are nothing more than a numeric parser combinators. -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] HOC is dead! Long live HOC!
BridgeSupport [1] is new functionality in Leopard that makes the current Haskell Objective-C bindings (HOC) obsolete (almost). --- The metadata is intended to be a resource for use beyond bridging. Most frameworks on the system provide two chunks of XML BridgeSupport metadata; succinct and full. The succinct version contains all of the metadata not provided by the Objective-C runtime (which provides about 80% of what is necessary to do full fidelity calls in / out of Objective-C via libffi). The full version contains just that, the full metadata required to describe the APIs of the framework, including all the bits that could be gleaned at runtime. --- BridgeSupport makes it unnecessary to parse Cocoa headers since all the required data is right there in plain XML [2]. It's no longer necessary to bundle libffi with HOC either since Leopard comes with a much improved version. I hereby propose to close up the old HOC project on SourceForge and set up a new one at GoogleCode. I already did this but GoogleCode noticed the SF project and is now waiting for permission from Wolfgang and Andre. Thanks, Joel [1] http://www.friday.com/bbum/2007/10/27/pyobjc-20-pyobjc-in-leopard/ [2] /System/Library/Frameworks/AppKit.framework/Resources/ BridgeSupport/AppKitFull.bridgesupport -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Memory-mapped arrays?
Is there such a thing as memory-mapped arrays in GHC? I'm looking for something that would let me memory-map a file of floats and access it as an array. Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Should I step into a minefield? / Writing a trading studio in Haskell
I need to pick among the usual list of suspects for a commercial product that I'm writing. The suspects are OCaml, Haskell and Lisp and the product is a trading studio. My idea is to write something like TradeStation [1] or NinjaTrader, only for the Mac. It would be quite nifty to use SPJ's financial combinator approach and, for example, embed Yi (Haskell editor). One of the key features of the product would be the ability to model your trading logic using a trading DSL. I'm thinking that this DSL could well be Haskell but I'm concerned about stepping into a minefield. I will need to embed GHC into the app, for example, and I understand that the GHC API does not offer unloading of code at the moment. I would prefer not to bundle GHC separately so I don't think the hs- plugins approach would work for me. Maybe I'm mistaken. Most of all, I'm concerned that my users will need to face the error reports from GHC and could get tripped by laziness, i.e. write something that would make the app run out of memory. Off the top of my head I can't figure out a way to limit what my users can do without analyzing the Haskell AST within the GHC API and complaining if necessary. Can someone with experience in offering a Haskell DSL to their users please comment? Notice that I'm not even mentioning being concerned with the unpredictable effects of laziness. There's probably a reason why Jane St Capital is using OCaml instead of Haskell. I'm not going to play in that league but my knee-jerk reaction is to use OCaml or Lisp and avoid laziness altogether. I just can't see how laziness can help in processing real-time price data. Thanks, Joel [1] http://www.tradestation.com/default_2.shtm [2] http://www.ninjatrader.com/webnew/index.htm -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: HOC is dead! Long live HOC!
On Nov 7, 2007, at 9:57 PM, Wolfgang Thaller wrote: One big piece of information we need that is currently missing from the BridgeSupport files is which declaration comes form which header file. HOC's module structure currently follows Apple's .h files, and we need the module system for resolving naming ambiguities. Why not assume that each class goes into a file of its own and all classes in a directory matching the name of the framework? You will then have AppKit/NSWindow.hs, etc. I think this is how it's done right now. Constants and such can be gathered in AppKit/AppKit.hs. I haven't had a chance recently to do a thorough comparison of different open source hosting providers, so I have no opinion on this one. So if you want to invest time in maintaining HOC, and you want to maintain it on GoogleCode, then so be it. How do I give my permission? Either you or Andre should have received an email from Google Code. Please add wagerlabs to the project admins on SourceForge and I'll look into it. Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] CPP, Leopard and Haskell Objective-C bindings
It seems that the current approach taken by HOC is to strip preprocessing directives. This may not have been a problem before Leopard but Cocoa header files are now full of macros in most unusual places, e.g. @interface NSObject (NSDeprecatedMethods) + (void)poseAsClass:(Class)aClass DEPRECATED_IN_MAC_OS_X_VERSION_10_5_AND_LATER; @end I'm trying to figure out the easiest way to run CPP over the header files before processing them in HOC. Is there a CPP written in Haskell and packaged as a library? Does someone have a quick Haskell solution for running CPP over a header file (with include paths?), redirecting into a temp file and reading that back into Haskell? Should I preprocess all Cocoa header files using make and then read these in? Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: CPP, Leopard and Haskell Objective-C bindings
On Nov 6, 2007, at 6:57 PM, Wolfgang Thaller wrote:
That is not exactly what we want, I think. Currently, HOC parses
things file-by-file, so we do NOT want to follow #include
directives. We might just process the line pragmas from CPP to keep
track of where things came from, OTOH.
You _do_ need to pre-process. Witness the following:
@interface NSWindow : NSResponder
#if MAC_OS_X_VERSION_MAX_ALLOWED = MAC_OS_X_VERSION_10_5
NSAnimatablePropertyContainer, NSUserInterfaceValidations
#else
NSUserInterfaceValidations
#endif
{
/*All instance variables are private*/
...
It breaks the HOC parser.
I'm still working on cleaning up my InterfaceGenerator rewrite (I
didn't have enough time to finihs last weekend, so maybe next
weekend, but at least I'm motivated now).
I'll be waiting anxiously.
I think any more more elaborate improvements to the interface
generator should be based on that instead of my old code.
Maybe I can merge my changes when you are ready. What are your
improvements to the interface generator?
Thanks, Joel
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[Haskell-cafe] Leopard: ghc 6.8.1 and the case of the missing _environ
Symptoms: You build 6.8.1 from source on Leopard (x86 in my case) and then junior:ghc-6.8.1 joelr$ ghci GHCi, version 6.8.1: http://www.haskell.org/ghc/ :? for help ghc-6.8.1: /usr/local/lib/ghc-6.8.1/lib/base-3.0.0.0/HSbase-3.0.0.0.o: unknown symbol `_environ' Loading package base ... linking ... ghc-6.8.1: unable to load package `base' Problem: ghc binaries are being stripped upon installation which eliminates _environ, e.g. junior:tmp joelr$ nm x|grep environ 2ff0 T ___hscore_environ 0004d004 D _environ junior:tmp joelr$ strip x junior:tmp joelr$ nm x|grep environ Solution: Need to make sure install-sh does _not_ use the -s option. Haven't found out where this needs to be done yet. A temporary workaround is to ask Manuel for the pre-built binaries. Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Embedding the GHC API
Has anyone tried to embed GHC as a library recently? What is the size of the resulting binary? I'm assuming a bare minimum of needed libraries. Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Quasiquotations part of GHC?
Folks, Did quasiquotations ever make it into the GHC tree? They were implemented as a patch to 6.7. Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Erlang VM in Haskell
On Aug 16, 2007, at 1:36 PM, Neil Bartlett wrote: However, wouldn't it be rather difficult, given that there doesn't seem to be a publicly available specification for the Erlang VM or the BEAM file format Very difficult, correct. I use Erlang daily, in fact Erlang is what brings bread to my table. I want to learn more about the Erlang insides so I'll simply dig in. Perhaps it would be interesting to look at a slightly more constrained problem: can Erlang's message passing model (including distributed messaging across a network) and process monitoring facilities be replicated in Haskell? My ultimate goal is to have a version of the Erlang VM that's suitable for running trading systems, i.e. one that allows high-speed numerics. I don't have much interest in replicating OTP in Haskell and Haskell may ultimately not be the right choice for what I envision. Thanks, Joel -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Erlang VM in Haskell
Folks, I would like to write an Erlang VM in Haskell. I first thought of OCaml but Haskell has SMP and lazy evaluation may come in handy. Plus, I'll need help in this project like in no other and support from the Haskell community has always been outstanding. I'm doing this to learn more about the Erlang internals and to acquire some skills in the process. I'm also hoping to be at least as fast as the existing Erlang VM (written in C) and to be able to extend the VM in a functional language. With C you can implement a threaded VM using GCC labels or switch- style [1]. What is the most efficient approach in Haskell? I'm thinking using CPS and building up a chain of closures. Would this work well? Any other suggestions? The Haskell repo for the initial HEM (Haskell Erlang Machine) is at http://darcs.haskell.org/hem. A much improved HAW implementation will follow in the not so near future. Thanks, Joel [1] http://www.complang.tuwien.ac.at/forth/threaded-code.html -- http://wagerlabs.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Picking an architecture for a Haskell web app
On May 10, 2007, at 10:01 AM, Bayley, Alistair wrote: Depends. Did you leave out WASH intentionally? http://www.informatik.uni-freiburg.de/~thiemann/WASH/ Nope, I forgot about it but looked at the Hemp app this morning. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Debugging
On May 10, 2007, at 10:19 AM, Jules Bean wrote: The 'next step' is to move from testing by hand in ghci to writing quickcheck properties / smallcheck / unit tests for the functions. I still don't understand the difference between QC and SC. Would someone kindly explain and provide an example or two of when SC should be used? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Telling Cabal not to install the executable
I tell Cabal to build library and a test harness. How can I tell Cabal that I only want the library installed? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Picking an architecture for a Haskell web app
Folks, I have finished an alpha version of my EasyLanguage [1] to C# compiler and need to deploy it on Amazon EC2/S3. The compiler web interface is very simple: paste EL code, get back C# code or the same EL code with the error highlighted. I view the site as more than just a compiler, though, and want a blog, forums, etc. Last but not least, I want to be able to update portions of the site without shutting it down. My choice seems to boil down to HAppS [2], HOPE [3], or a combination of Ruby/Rails with Lambdabot. At first glance, HAppS lacks publishing (my ultimate need) but promises an interface to S3 sometime in the future. My understanding is that it's ready but is not being released. HAppS is heavy on features that I may not make use of. I had a hard time understanding the HPaste [4] code written using HAppS and I don't fancy using XSLT as my HTML template language. HOPE has a publishing framework (blog, RSS, comments). I could write the forums or just use Google Groups. I like the module system and the FCGI interface should let me couple HOPE with Lighty [5]. The HOPE code base looks clean and simple and I'm guessing that adding Lambdabot-style dynamic loading of modules would be straightforward. Overall, HOPE has everything that I need, without unnecessary extras. It does not have an interface to Amazon S3, though, and I would need that to rewrite the storage bits to use S3 instead of a regular database. Lambdabot by itself doesn't offer much apart from robust dynamic loading of Haskell code. Its features have been heavily tested, though, which gives me a warm feeling. I'm thinking that the same hot- loading technology that Lambdabot uses could be coupled with either HAppS or HOPE. Lambdabot has a FCGI which should make mixing it with HOPE particularly easy. Going with Ruby and Rails I will have everything I need and more. The compiler could run in a separate server (think Lambdabot) but I would need to manage two different platforms. Is my assessment correct? Did I miss anything? What approach do you favor? Thanks, Joel P.S. I have the same compiler written in OCaml which is what I started with. Developing it has been a relative breeze but deploying on the web was a tale of frustration. I gave up and finished the Haskell version. [1] http://lambda-the-ultimate.org/node/2201 [2] http://happs.org/HAppS/README.html [3] http://hope.bringert.net/about [4] http://hpaste.org [5] http://www.lighttpd.net/ -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Indenting with PPrint
Brandon, On May 8, 2007, at 12:33 AM, Brandon Michael Moore wrote: braces x = group (PP. braces (nest 4 (linebreak x) linesbreak) I ended up with the following: nest = PP.nest 4 braces x = nest (lbrace $ x) $ rbrace If you happen to be formatting C I've also worked out how to get nice argument lists out of both pretty printers. I'm formatting C# but I'll certainly take your arg list tips. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Co-arbitrary
Would someone kindly explain why we need co-arbitrary in QuickCheck and how to define it? Detailed examples would be awesome! I would be willing to paste an in-depth explanation on my wall and keep it forever. Thanks in advance, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] QuickCheck invariants for AST transformations
I'm looking for suggestions on how to create invariants for the following AST transformation code. Any suggestions are appreciated! I asked this question before and Lennart suggested abstract interpretation as a solution. This would require interpreters for both ASTs to determine that the result they achieve is the same. I don't fancy writing a C# interpreter, though, so I'm looking for an easier way out. Thanks, Joel [1] http://tinyurl.com/368whq --- instance SharpTransform C.Type Type where toSharp C.TyInt = return TyInt toSharp C.TyFloat = return TyFloat toSharp C.TyStr = return TyStr toSharp C.TyBool = return TyBool toSharp (C.TyArray x) = liftM2 TyArray (toSharp x) (return []) toSharp (C.TySeries C.TyFloat) = return $ TyCustom DataSeries toSharp (C.TySeries x) = error $ Unsupported series type: ++ show x toSharp (C.TyProp x) = toSharp x toSharp C.TyUnit = return TyVoid instance SharpTransform C.VarIdent VarIdent where toSharp (C.VarIdent x) = return $ VarIdent x instance SharpTransform (Maybe C.Expr) (Maybe Expr) where toSharp Nothing = return Nothing toSharp (Just e) = liftM Just (toSharp e) instance SharpTransform C.Subscript [Expr] where toSharp xs = mapM toSharp xs instance SharpTransform C.BarsAgo Expr where toSharp C.Now = return $ Int 0 toSharp (C.BarsAgo e) = toSharp e -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Indenting with PPrint
Folks,
Are you using UU.PPrint [1]? Can you tell me how to print stuff like
this?
{
blah
blah
}
I tried the following which sort of works but doesn't return the
closing brace to the indentation level of the first one.
braces x = PP.braces $ linebreak indent 4 x
Thanks, Joel
[1] http://tinyurl.com/25t6xz
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[Haskell-cafe] Re: [Haskell] Newbie: what are the advantages of Haskell?
The biggest advantage of Haskell to me is that it helps me write better programs in other languages. For one reason or another Haskell never turns out to be my final implementation language my my programs gain in the process. Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Is Template Haskell a suitable macro language?
I'm finding myself dealing with several large abstract syntax trees that are very similar in nature. The constructor names would be the same or one type may be a small extension of another. This is something that I wouldn't worry about with Lisp, for example, as I would create a bunch of macros for creating syntax trees and reuse them all over. I cannot do this in Haskell, though, as my macros are functions and so I must repeat them for every AST since they return different types. I'm wondering if Template Haskell is a suitable replacement for Lisp macros. What is the consensus? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Creating QuickCheck properties
Folks,
I have code like this that I want to test with QuickCheck but I'm
having trouble imagining how I would wrap it up in a property.
Do I make sure that id, subs, back are always morphed properly or do
I leave that to separate properties for their respective types?
Do I then ensure that array types are always unwrapped (see getType
below), that a series variable is always declared, code added and a
series reference returned?
Last but not least, is monadic testing part of Test.QuickCheck.*?
Thanks, Joel
type Core a = State CoreUnit a
data CoreUnit
= Core
{ coreSym :: Integer -- starting # for gensym
, coreVars :: M.Map String VarDecl
, coreCode :: M.Map Integer [Statement]
}
deriving (Show, Eq)
morphHistArrayAccess :: VarIdent - Subscript - BackRef - C.Core
C.Expr
morphHistArrayAccess id subs back = do
id' - morph id
subs' - morph subs
back' - morph back
(C.TyArray ty) - getType id'
s - genSym series
addVar s (C.TySeries ty) [] Nothing
addCodeFront 1 [ C.AddToSeries (C.VarIdent s) (C.Var id' subs') ]
return $ C.Series (C.VarIdent s) back'
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[Haskell-cafe] QuickCheck testing of AST transformers
My previous post did not receive any replies so I thought I might try generalizing the problem a bit... Suppose I'm parsing a language into a syntax tree and then transforming that tree into another AST representing a core language. The core language is a more general AST that should help with compiling to other languages. My problem is how to best structure my AST transformations to be able to test them with QuickCheck. I suspect that I'm not going about it in the most optimal way so I thought I should ask for suggestions. The transformation into the core AST applies operations to simplify, or desugar, the AST of the original language. Here's sample code in the source language which, incidentally, was recently highlighted at Lambda the Ultimate [1]. Array: MyArray[10](10 + 2); Value1 = MyArray[5][10]; This declares an array of 10 elements and initializes each element to 12. Value1 (a built-in variable) is then initialized to the value of element #5 as of 10 bars ago. A bar is, basically, a stock quote. The code is invoked on every bar and so 5 bars ago can be treated as 5 invocations ago. The syntax tree of the above code is a 1-1 mapping. We declare an array of integers of 10 elements. Initialize it to the sum of two integers and then assign to Value1. [ ArrayDecs [ VarDecl (VarIdent MyArray) TyInt [Int 10] (Op Plus (Int 10) (Int 2)) ] , Assign (VarIdent Value1) [] (Var (VarIdent MyArray) [Int 5] (BarsBack (Int 10))) ] The desugared version does away with the array declaration statement and declares MyArray to be a variable of array type. Arrays in the core language do not remember values from one invocation to another but there's a data series type, so we declare a series variable to hold the value of element #5. We must manually store the value of the array element in the data series and can then refer to the value of the series 10 data points ago. vars = [ (MyArray, VarDecl (TyArray TyInt) [Int 10] (Just (Plus (Int 10) (Int 2 , (series0, VarDecl (TySeries TyInt) [] Nothing) ] code = [ AddToSeries (VarIdent series0) (Var (VarIdent MyArray) [Int 5]) , Assign (Var (VarIdent Value1) []) (Series (VarIdent series0) (Int 10)) ] The next step would be to take the above core syntax tree and transform it yet again into a C# (or other target language) AST. It's assumed that all target languages have a data series type. The OCaml version of my code translated directly into the C# AST but I figured an intermediate syntax tree will help me translate into other languages such as Haskell, Erlang or OCaml. The part I can't figure out is how to come up with a set of invariants for my transformations. Should I, for example, state that every access to an array value in a previous invocation should introduce an extra variable to hold the series plus the appropriate assignment code? Should I write the translator as a series of small transformers in the ST monad that can be threaded and tested separately? Thanks in advance, Joel [1] http://lambda-the-ultimate.org/node/2201 -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: QuickCheck subsumes unit testing
On Apr 21, 2007, at 2:54 AM, Donald Bruce Stewart wrote: Just to walk the walk, and not just talk the talk, here's a quick unit testing 'diff' driver I hacked up for QuickCheck. Yay! I'll be the first to switch over! Note that we actually probably want to use SmallCheck here, I don't have an idea of when to prefer SmallCheck over QuickCheck. An explanation and, possibly, a tutorial would be very welcome! Anyone? Note also, the driver would need further extending, since we've changed the structure of the Testable values. Can you elaborate on further extending? What direction should I extend it in? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Writing guards shorthand
Support I want to infer the type given an Op that looks like this (incomplete): data Op = Minus | Plus | Mul | LT | GT Is there a shorthand way of bunching Minus, Plus and Mul in a function guard since they all result in TyNum whereas the rest in TyBool? I really don't want several function clauses and neither do I want separate guards for every constructor. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Writing guards shorthand
This is what want. Notice the succinctness. Objective Caml version 3.10+dev24 (2007-02-16) # type foo = A | B | C | D | E | F ;; type foo = A | B | C | D | E | F # A;; - : foo = A # let infer = function | A | B | C - true; | D | E | F - false;; val infer : foo - bool = fun # infer A;; - : bool = true # infer B;; - : bool = true # infer D;; - : bool = false # infer F;; - : bool = false # -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: Writing guards shorthand
On Apr 19, 2007, at 4:10 PM, Jón Fairbairn wrote: Is there some reason why you don't want data Op = Aop Aop | Bop Bop data Aop = Minus | Plus | Mul data Bop = LT | GT It's a long story. The short version is that the above will complicate my AST a whole lot. I had it this way before. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Morphing ASTs and scrapping boilerplate code
Folks,
I'm transforming ASTs as part of my compiler from one language into
another. The source AST is a list of statements whereas the target
AST is a class definition.
type Object a = State Obj a
data Obj
= Object
{ objSym :: Integer -- starting # for gensym
, objVars :: M.Map String VarDecl
, objProps :: M.Map String PropDecl
, objMeths :: M.Map String MethodDecl
}
deriving (Show, Eq)
I'm using a state monad and the transformations are supposed to
update the state (object) as needed to add variables, methods, etc.
class Morpher a b | a - b where
morph :: a - Object b
I have a lot of boilerplate code like this and wonder how I can
scrape it.
instance Morpher Type C.Type where
morph TyInt = return C.TyInt
morph TyFloat = return C.TyFloat
morph TyStr = return C.TyStr
morph TyBool = return C.TyBool
morph TyColor = return C.TyColor
morph TyStyle = return C.TyStyle
morph (TyList ty) = liftM C.TyList (morph ty)
morph (TyArray ty) = liftM C.TyArray (morph ty)
morph (TySeries ty) = liftM C.TySeries (morph ty)
morph (TyInput ty) = liftM C.TyProp (morph ty)
morph (TyRef ty) = liftM C.TyRef (morph ty)
morph TyUnit = return C.TyUnit
morph TyPrintDest = return C.TyPrintDest
Notice that I'm calling a constructor of the same name in a different
module ... unless it's an exception.
instance Morpher BackRef C.Expr where
morph Now = C.Int 0
morph (BarsBack e) = morph e
instance Morpher DataRef C.Expr where
morph (DS x) = C.Int x
How can I reduce the boilerplate here?
Thanks, Joel
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[Haskell-cafe] Re: Morphing ASTs and scrapping boilerplate code
Just to clarify, I really liked the SYB solution to my previous issue with stripping token locations. It looked like this: strip :: (Data a) = a - a strip = everywhere (mkT f) where f (TokenPos a _) = a f x = x In the general AST transformation case, my constructor name is the same and so is the number of arguments. So, yes, it's a different type but it's a derivative of Data and Typeable just like the original type. Conceptually, I want to lookup the new type from a given module, using the same constructor name as the original type. Then I want to apply morph to every argument of the source constructor and give the resulting values to the new constructor. Lastly, I would like to write pattern matches for special cases (see TokenPos above) and write out the transformation by hand. My ASTs are quite large and there aren't that many special cases. Thanks, Joel On Apr 19, 2007, at 5:11 PM, Joel Reymont wrote: instance Morpher Type C.Type where ... morph (TyList ty) = liftM C.TyList (morph ty) morph (TyArray ty) = liftM C.TyArray (morph ty) morph (TySeries ty) = liftM C.TySeries (morph ty) morph (TyInput ty) = liftM C.TyProp (morph ty) morph (TyRef ty) = liftM C.TyRef (morph ty) morph TyUnit = return C.TyUnit morph TyPrintDest = return C.TyPrintDest -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] SYB and opaque types
Suppose I need to manually derive Data and Typeable for SourcePos from Parsec to make sure my code compiles. I won't actually be running the code I manually derive since the constructor that includes SourcePos will be skipped. With Neil Mitchell's (and #haskell) help I'm doing this to strip token locations from my AST: import Data.Generics import qualified Text.ParserCombinators.Parsec as P instance Data SourcePos where gfoldl r k x = k x typename_SourcePos = mkTyCon SourcePos instance Typeable SourcePos where typeOf _ = mkTyConApp typename_SourcePos ([]) strip = everywhere (mkT f) where f (TokenPos a _) = a f x = x I know that the warnings about gunfold, toConstr and dataTypeOf are harmless but how would I define them to avoid the warnings? Also, the definition of strip above requires -fno-monomorphism- restriction. Should I not worry about it? The code runs just fine, locations are being stripped and tests pass. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Zero-arity tests in QuickCheck and displaying expected result
On Apr 17, 2007, at 9:31 AM, Ketil Malde wrote: Prelude Test.QuickCheck let prop0 = List.sort [3,2,1] == [1,2,3] in quickCheck prop0 OK, passed 100 tests. My point is to be able to see that result generated was X and that it did not match expected Y, where both X and Y are printed out. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Zero-arity tests in QuickCheck and displaying expected result
On Apr 16, 2007, at 9:29 PM, Donald Bruce Stewart wrote: It's interesting to note that QuickCheck generalises unit testing: zero-arity QC properties are exactly unit tests. I don't think this works very well. I rely quite heavily on being able to compare expected output with test results and QC does not seem to provide for this feature when tests are zero arity. Am I missing something? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Zero-arity tests in QuickCheck and displaying expected result
Are there any examples of such custom drivers? On Apr 16, 2007, at 10:09 PM, Donald Bruce Stewart wrote: That's just the default driver. Plenty of custom drivers exist which compare the output. The QC driver is just a function you implement, after all. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Zero-arity tests in QuickCheck and displaying expected result
That's what HUnit does but it's enticing to be able to standardize on QuickCheck for all of your testing. On Apr 16, 2007, at 10:11 PM, Lennart Augustsson wrote: Why can't you just do 'f 1 2 3 == (4, 5, 6, 7)' to test f? -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parallel executing of actions
On Apr 15, 2007, at 8:23 PM, Spencer Janssen wrote: parSequence_ xs = do m - newEmptyMVar mapM_ (\x - forkIO x putMVar m ()) xs replicateM_ (length xs) (takeMVar m) mapM_ above spawns (length xs) threads blocking on a single lock, right? replicateM_ then makes sure that the lock is unlocked as many times as threads spawned, right? Since all the threads block on a single MVar how do they run in parallel? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Type checking with Haskell
Folks, The ghc/compiler/typecheck directory holds a rather large body of code and quick browsing through did not produce any insight. How do you implement type checking in haskell? Assume I have an Expr type with a constructor per type and functions can take lists of expressions. Do I create a function taking an Expr, pattern-matching on appropriate constructor and returning True on a match and False otherwise? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Type checking with Haskell
On Apr 12, 2007, at 1:07 PM, Stefan Holdermans wrote: You might want to check out Typing Haskell in Haskell [1] by Mark P. Jones. Must be _the_ paper as Don suggested it as well. I also looked at my copy of Andrew Appel's compilers in ML book and realized that I should be going about it differently than I thought, i.e. figuring out and returning the type of an expression rather than matching constructors. Oh, well. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Typing non-Haskell in Haskell
I feel I should set aside a Friday of every week just to read the Haskell papers :-). After skimming through Typing Haskell in Haskell I have a couple of questions... Are type constructors (TyCon) applicable to Haskell only? Mine is a Pascal-like language. How would I type Pascal functions as opposed to Haskell ones? It seems that the approach is the same and I still need TyCon (-). Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Type checking with Haskell
Thanks Stefan! On Apr 12, 2007, at 3:00 PM, Stefan O'Rear wrote: Your problem, as I understand it, is even simpler than most since there are no higher order functions and no arguments. I do have functions and arguments but I don't have HOF. (That said, it would probably be better to fuse parsing and type checking in this case so that you do not need to track source positions.) I'm not sure how to do this, quite honestly. The language is dynamically typed so I have to infer variable types from their usage, function return types from what is assigned to the function name (last assignment in program, Fun = xxx). I also have to infer if variables are of a series type by checking if any references are made to the previous values of those variables. I don't think it's possible to fuse type checking with parsing here. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Type checking with Haskell
On Apr 12, 2007, at 3:00 PM, Stefan O'Rear wrote: Also, GHC runs typechecking *before* desugaring, apparently thinking error messages are more important than programmer sanity :) What would be the benefit of running type checking after desugaring? -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Left-factoring with Parsec
How does
expr = b a*
translate back into the grammar? Assuming that I had b, c, d...
expr = b | c | d | many (do { symbol :; expr; symbol :;
expr })
Like this?
Thanks, Joel
On Apr 11, 2007, at 8:56 PM, Lennart Augustsson wrote:
I presume your grammar has other clauses for expr, otherwise the
loop is inevitable.
Assuming you have other clauses you can always left-factor.
Here's how those of us with weak memory can remember how to do it:
Say that you have
expr ::= expr : expr : expr
| b
Let's call the part from the first : a, since it doesn't matter
what it is. So we have
expr ::= expr a | b
Let's call expr x, and just change notation slightly
x = x a + b
Now use high school algebra
x = x*a + b
x - x*a = b
x*(1-a) = b
x = b / (1-a)
x = b * 1/(1-a)
Now you have to remember that the Taylor series expansion of 1/(1-
a) is
1/(1-a) = 1 + a + a^2 + a^3 + a^4 + ...
OK, now put your grammar hat back on. What's
1 | a | aa | aaa | | ...
it's just an arbitrary number of a:s, i.e., a* (or 'many a' in
parsec).
So finally
expr = b a*
-- Lennart
On Apr 11, 2007, at 18:15 , Joel Reymont wrote:
Suppose I have expr = expr : expr : expr.
Can the above be left-factored to fail on empty input so that my
parser doesn't go into a loop?
Thanks, Joel
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[Haskell-cafe] Left-factoring with Parsec
Suppose I have expr = expr : expr : expr. Can the above be left-factored to fail on empty input so that my parser doesn't go into a loop? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Skipping keywords with Parsec
Is there a way to have any Parsec combinator skip a certain set of keywords? I tried lexeme = P.lexeme lexer . (skip ) but I don't think lexeme is called for every keyword. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Skipping keywords with Parsec
Just in case I wasn't clear enough, I'm asking about skipping keywords represented by the skip combinator that can be located anywhere within the input. I do know about skipMany and skipMany1, in fact skip is defined in terms of these. On Apr 11, 2007, at 9:04 PM, Joel Reymont wrote: Is there a way to have any Parsec combinator skip a certain set of keywords? I tried lexeme = P.lexeme lexer . (skip ) but I don't think lexeme is called for every keyword. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parsec: Help needed with simple parser
On Apr 10, 2007, at 3:42 AM, Albert Y. C. Lai wrote: Does option help? Like: It did, together with a couple of 'try's. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Type checking and locating token with Parsec
Folks, Imagine a language where Num + Num yields a Num and Str + Num yields a Str but Num + Str should not be allowed. I implemented parsing for such a language in OCaml with a yacc-based parser without an additional type-checking pass, entirely within the yacc grammar. I tried to take such an approach with Parsec but hit the roadblock with buildExpressionParser since it returns the same type as the token parser given to it. Rather than have numerical expressions, string expressions, etc., as separate types, I simplified things down to a single expression type that holds my booleans, strings and numbers. I now need to implement type checking of my parsed AST. The main issue is error reporting. I'm not sure where to get token location with Parsec and how to elegantly embed it in my AST. Has anyone implemented type checking on top of a Parsec-based parser? How did you locate your tokens? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Grabbing list of functions from current module
Folks, Does anyone have code that can grab a list of functions named with a certain prefix from the current (or given) module? I want to find functions named, say, ast_* and produce a list of tuples like (input1, ast_input1). Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Grabbing list of functions from current module
Mea culpa! I meant Template Haskell code :-). Thanks John! On Apr 9, 2007, at 2:02 PM, John Meacham wrote: sed -ne 's/^ast_\([a-z0-9_A-Z]\+\).*$/(\1,ast_\1)/p' File.hs note the two occurances of 'ast_'. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Parsec: buildExpressionParser of a different type than parsed term
Folks, I'm trying to parse NumExpr NumExpr (example) which should return a logical expression while parsing numeric terms. I can't figure out how to make buildExpressionParser do this for me since it takes the type of the term parser given to it. If I supply a parser for numeric terms then I cannot return a logical expression. How can this be resolved? Note that I do not want to put all expressions into the same Expr type since it makes generating valid random ASTs with QuickCheck impossible. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parsec: buildExpressionParser of a different type than parsed term
Albert, On Apr 10, 2007, at 12:19 AM, Albert Y. C. Lai wrote: As you probably suspect, one single use of buildExpressionParser cannot accomplish it. It is equivalent to the problem of homogeneous lists. The issue is that I need buildExpressionParser to parse numerical expression but return logical ones, i.e. data CondExpr = CondExpr Op NumExpr NumExpr The way b-E-P is set up it wants NumExpr to be its return type and thus I cannot return a CondExpr. I'm still scratching my head but in all likehood I'll have to hack a custom version of b-E-P. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Parsec: Help needed with simple parser
Folks, I wrote a parser for what should be a simple expression but it's not working. Any help is appreciated! My expression is x + 1 where x can be either Close, or Close[N] or Close[N] of DataM where N and M are positive integers. What happens in my case is that 1 + x parses fine but x + 1 doesn't. In fact, I would be fine with parsing Close + such that it ignores the plus and returns the parse. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] MPTC and type classes issue (polymorphic '+')
Folks,
I'm trying to save time when typing in my ASTs so I thought I would
create a Plus class like this (I do hide the one from Prelude)
class PlusClass a b c | a b - c where
(+) :: a - b - c
{-
instance (Integral a, Integral b) = PlusClass a b Expr where
a + b = NumExpr (NumOp Plus (Int (fromIntegral a)) (Int
(fromIntegral b)))
instance Integral a = PlusClass a Double Expr where
a + b = NumExpr (NumOp Plus (Int (fromIntegral a)) (Double b))
-}
instance PlusClass Integer Integer Expr where
a + b = NumExpr (NumOp Plus (Int a) (Int b))
instance PlusClass Double Integer Expr where
a + b = NumExpr (NumOp Plus (Double a) (Int b))
instance PlusClass NumExpr NumExpr Expr where
a + b = NumExpr (NumOp Plus a b)
instance PlusClass Integer NumExpr Expr where
a + b = NumExpr (NumOp Plus (Int a) b)
instance PlusClass NumExpr Integer Expr where
a + b = NumExpr (NumOp Plus a (Int b))
instance PlusClass String String Expr where
a + b = StrExpr (StrOp StrPlus (Str a) (Str b))
NumExpr and StrExpr return Expr whereas Int, Double return NumExpr
and Str returns StrExpr.
This is all so that I could type in
input2 =
[ InputDecs [ inp emaLength TyNumber (20 + 40) ] ]
Still, I get the following error
Easy/Test/ParserAST.hs:76:44:
No instance for (PlusClass t t1 Expr)
arising from use of `+' at Easy/Test/ParserAST.hs:76:44-50
Possible fix: add an instance declaration for (PlusClass t t1 Expr)
In the third argument of `inp', namely `(20 + 40)'
In the expression: inp emaLength TyNumber (20 + 40)
In the first argument of `InputDecs', namely
`[inp emaLength TyNumber (20 + 40)]'
and get an overlapped instances error if I uncomment the top portion.
Any suggestions on how to resolve this?
Thanks, Joel
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Re: [Haskell-cafe] MPTC and type classes issue (polymorphic '+')
Pepe, On Apr 7, 2007, at 1:31 PM, Pepe Iborra wrote: input2 = [ InputDecs [ inp emaLength TyNumber ((20::Integer) + (40::Integer)) ] ] Thank you for your suggestion! I'm trying to make my AST definition as succinct as possible, though, so I would really love to have 20 + 40. The issue is confined to a single module used during testing. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MPTC and type classes issue (polymorphic '+')
This is the related paste: http://hpaste.org/1291#a9 -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MPTC and type classes issue (polymorphic '+')
Pepe,
On Apr 7, 2007, at 2:01 PM, Pepe Iborra wrote:
And without the Integral assumption, you cannot define your
instance. So what I would do is to create a thin wrapper:
i = id :: Integer - Integer
and write:
input2 = [ InputDecs [ inp emaLength TyNumber ((i 20) + (i
40)) ] ]
That's what I did but I'm driving to make it even simpler.
I would like to add various permutations of Integer, Double and
NumExpr, as well as String and StrExpr. This includes Integer/
Integer, Integer/Double, Double/NumExpr, etc.
This is standalone code, also at http://hpaste.org/1291#a12
{-# OPTIONS -fglasgow-exts -fallow-overlapping-instances #-}
import Prelude hiding ( id, (+), (-), (/), (*), (), GT, EQ, LT )
newtype VarIdent = VarIdent String
instance Show VarIdent
instance Eq VarIdent
data NumExpr
= Int Integer
| Double Double
| NumOp NumOp NumExpr NumExpr
data StrExpr
= Str String
| StrOp StrOp StrExpr StrExpr
data Expr
= NumExpr NumExpr
| StrExpr StrExpr
data Type = TyNumber | TyString
data NumOp = Plus | Minus -- ...
data StrOp = StrPlus
data Statement
= Skip
| InputDecs [InputDecl]
data InputDecl
= InputDecl VarIdent Type Expr
class PlusClass a b c | a b - c where
(+) :: a - b - c
-- instance PlusClass a b c = PlusClass b a c
instance (Integral a, Integral b) = PlusClass a b Expr where
a + b = NumExpr (NumOp Plus (Int (fromIntegral a)) (Int
(fromIntegral b)))
instance Integral a = PlusClass a Double Expr where
a + b = NumExpr (NumOp Plus (Int (fromIntegral a)) (Double b))
instance PlusClass Integer Integer Expr where
a + b = NumExpr (NumOp Plus (Int a) (Int b))
instance PlusClass Double Integer Expr where
a + b = NumExpr (NumOp Plus (Double a) (Int b))
instance PlusClass NumExpr NumExpr Expr where
a + b = NumExpr (NumOp Plus a b)
instance PlusClass Integer NumExpr Expr where
a + b = NumExpr (NumOp Plus (Int a) b)
-- and the functions
id = VarIdent
inp x ty e = InputDecl (id x) ty e
input2 =
[ InputDecs [ inp emaLength TyNumber (20 + 40) ] ]
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Re: [Haskell-cafe] MPTC and type classes issue (polymorphic '+')
On Apr 7, 2007, at 2:01 PM, Pepe Iborra wrote: So what I would do is to create a thin wrapper: i = id :: Integer - Integer and write: input2 = [ InputDecs [ inp emaLength TyNumber ((i 20) + (i 40)) ] ] I do it like this and it does save typing. It's not bad so I'll stick to it for now: id = VarIdent d = Double i = Int b = Bool s = Str d' = NumExpr . d i' = NumExpr . i b' = CondExpr . b s' = StrExpr . s n = NumExpr (+) a b = NumExpr (NumOp Plus a b) This is much less verbose than my OCaml version anyway. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] MPTC and type classes issue (polymorphic '+')
On Apr 7, 2007, at 4:16 PM, Stefan O'Rear wrote: You can probably use -fallow-incoherent-instances for this. It has a scary name on purpose since it doesn't usually do what you think it should... My (very limited!) understanding of type checking algorithms says that in this case, the worst that can fail is an extra call to fromInteger :: Integer - Integer. Big deal. It only works until I add instance declarations for Fractional. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] How can I refactor this code?
http://hpaste.org/127 It looks quite ugly to me so any help is appreciated! Thanks in advance, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: How can I refactor this code?
That would be http://hpaste.org/1278, my apologies! -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
Stefan, Data.Derive is a most awesome piece of code! Is there soemething in DrIFT that you did not like that made you write it? Thanks a lot! On Apr 5, 2007, at 12:48 AM, Stefan O'Rear wrote: Data.Derive can do this. In an attempt to avoid munging the relevent files they are attached. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[2]: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
Following tells me that Data.Derive.Peephole was built. ar t dist/build/libHSderive-0.1.a says Derive.o is there. ghc-pkg -l /opt/local/lib/ghc-6.6/package.conf: Cabal-1.1.6, FilePath-0.11, GLUT-2.0, HUnit-1.1, OpenGL-2.1, QuickCheck-1.0, base-2.0, cgi-2006.9.6, derive-0.1, fgl-5.2, (ghc-6.6), haskell-src-1.0, haskell98-1.0, html-1.0, mtl-1.0, network-2.0, parsec-2.0, readline-1.0, regex-base-0.71, regex-compat-0.71, regex-posix-0.71, rts-1.0, stm-2.0, template-haskell-2.0, time-1.0, unix-1.0, xhtml-2006.9.13 derive-1.0 is in the list of packages. ghc --make FunParser.hs FunParser.hs:4:7: Could not find module `Data.Derive.Peephole': Use -v to see a list of the files searched for. I'm baffled again. --- runhaskell Setup.hs build Preprocessing library derive-0.1... Preprocessing executables for derive-0.1... Building derive-0.1... [1 of 9] Compiling Data.Derive.FixedPpr ( Data/Derive/FixedPpr.hs, dist/build/Data/Derive/FixedPpr.o ) [2 of 9] Compiling Data.Derive ( Data/Derive.hs, dist/build/Data/ Derive.o ) [3 of 9] Compiling Data.Derive.SYB ( Data/Derive/SYB.hs, dist/build/ Data/Derive/SYB.o ) [4 of 9] Compiling Data.Derive.TH ( Data/Derive/TH.hs, dist/build/ Data/Derive/TH.o ) [5 of 9] Compiling Data.Derive.BinaryDefer ( Data/Derive/ BinaryDefer.hs, dist/build/Data/Derive/BinaryDefer.o ) [6 of 9] Compiling Data.Derive.Eq ( Data/Derive/Eq.hs, dist/build/ Data/Derive/Eq.o ) [7 of 9] Compiling Data.Derive.Peephole ( Data/Derive/Peephole.hs, dist/build/Data/Derive/Peephole.o ) [8 of 9] Compiling Data.Derive.Binary ( Data/Derive/Binary.hs, dist/ build/Data/Derive/Binary.o ) [9 of 9] Compiling Data.Derive.Play ( Data/Derive/Play.hs, dist/build/ Data/Derive/Play.o ) ar: creating archive dist/build/libHSderive-0.1.a [1 of 1] Compiling Main ( Derive.hs, dist/build/derive/ derive-tmp/Main.o ) Linking dist/build/derive/derive ... sudo runhaskell Setup.hs install Installing: /usr/local/lib/derive-0.1/ghc-6.6 /usr/local/bin derive-0.1... Registering derive-0.1... Reading package info from .installed-pkg-config ... done. Saving old package config file... done. Writing new package config file... done. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
Stefan, What version of ghc are you using? Mine is 6.6. Data/Derive/Play.hs:9:7: Could not find module `Control.Monad.State': it is a member of package mtl-1.0, which is hidden I commented out that import line. Preprocessing library derive-0.1... Preprocessing executables for derive-0.1... Building derive-0.1... [1 of 9] Compiling Data.Derive.FixedPpr ( Data/Derive/FixedPpr.hs, dist/build/Data/Derive/FixedPpr.o ) [2 of 9] Compiling Data.Derive ( Data/Derive.hs, dist/build/Data/ Derive.o ) [3 of 9] Compiling Data.Derive.SYB ( Data/Derive/SYB.hs, dist/build/ Data/Derive/SYB.o ) [4 of 9] Compiling Data.Derive.TH ( Data/Derive/TH.hs, dist/build/ Data/Derive/TH.o ) Data/Derive/TH.hs:25:26: No instance for (Functor Q) arising from use of `fmap' at Data/Derive/TH.hs:25:26-31 Possible fix: add an instance declaration for (Functor Q) In the first argument of `(.)', namely `fmap f' In the expression: (fmap f) . deriveOne In the definition of `derive': derive (Derivation f _) = (fmap f) . deriveOne This I don't know how to deal with. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
On Apr 5, 2007, at 11:04 AM, Joel Reymont wrote: This is in Language.Haskell.TH.Syntax which is imported at the top of Data/Derive/TH.hs so I don't understand the cause of the error Apparently instance Functor Q was added to 6.6 very recently and it's not in MacPorts yet. I decided to throw down the gauntlet and run 6.7 instead. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
That did it, thanks! On Apr 5, 2007, at 12:07 PM, Twan van Laarhoven wrote: instance Functor Q where fmap = liftM -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[2]: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
Installed derive, trying to load it with ghci -package derive Loading package base ... linking ... done. Loading package template-haskell ... linking ... done. Loading package FilePath-0.11 ... linking ... done. ghc-6.6: unknown symbol `_derivezm0zi1_DataziDeriveziPeephole_zdf7_closure' Loading package derive-0.1 ... linking ... ghc-6.6: unable to load package `derive-0.1' What am I doing wrong? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
This is in Language.Haskell.TH.Syntax which is imported at the top of Data/Derive/TH.hs so I don't understand the cause of the error instance Functor Q where fmap f (Q x) = Q (fmap f x) Copying the above into TH.hs gives me Preprocessing library derive-0.1... Preprocessing executables for derive-0.1... Building derive-0.1... [4 of 9] Compiling Data.Derive.TH ( Data/Derive/TH.hs, dist/build/ Data/Derive/TH.o ) Data/Derive/TH.hs:23:10: Not in scope: data constructor `Q' Data/Derive/TH.hs:23:17: Not in scope: data constructor `Q' But Q is exported by Languave.Haskell.TH.Syntax !!! Any suggestions? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Re[2]: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
This is the exposed modules portion of derive.cabal. I had to remove the empty lines since Cabal was complaining about them. I suspect one of these lines had Data.Derive.Peephole in it. Exposed-Modules: Data.Derive Data.Derive.FixedPpr Data.Derive.SYB Data.Derive.TH Data.Derive.Binary Data.Derive.BinaryDefer Data.Derive.Eq Data.Derive.Play On Apr 5, 2007, at 12:46 PM, Joel Reymont wrote: FunParser.hs:4:7: Could not find module `Data.Derive.Peephole': Use -v to see a list of the files searched for. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
With derive compiled and installed I thought I would change the code
a bit and try it...
ghci -fth -v0 -e '$( _derive_print_instance makeFunParser
Foo )' baz.hs
baz.hs:30:3: Not in scope: `a1'
Any help is appreciated!
Thanks, Joel
---
FunParser.hs:
module FunParser where
import Data.Derive
import Data.Derive.Peephole
import Data.List
import Text.ParserCombinators.Parsec ( CharParser )
makeFunParser = Derivation drv FunParser
drv dat@(DataDef name arity ctors) =
simple_instance FunParser dat [funN parse [ sclause [] body ] ]
where
body = l1 choice $ lst [ clause con | con - ctors ]
clause con = l1 reserved (lit (trim (ctorName con)))
: args con (ctorArity con)
trim = reverse . takeWhile (/= '.') . reverse
args ct 0 = return' (ctp ct 'a')
args ct k = l1 char (lit '(') : args' ct k 0
args' ct remn seen = l0 parse
=: (('a' : show seen)
-: args'' ct (remn-1) (seen+1))
args'' ct 0 seen = l1 char (lit ')') : return' (ctp ct 'a')
args'' ct k seen = l1 char (lit ',') : args' ct k seen
class FunParser a
where parse :: CharParser s a
baz.hs:
import Text.ParserCombinators.Parsec hiding ( parse )
import qualified Text.ParserCombinators.Parsec.Token as T
import Text.ParserCombinators.Parsec.Language( emptyDef )
import Data.Derive.TH
import FunParser
data NumExpr
= Int Integer
| Num Double
instance FunParser NumExpr where
parse = numExpr
data Foo
= Foo NumExpr
lexer = T.makeTokenParser emptyDef
identifier = T.identifier lexer
reserved = T.reserved lexer
integer = T.integer lexer
float = T.float lexer
numExpr :: GenParser Char a NumExpr
numExpr =
choice [ integer = return . Int
, float = return . Num
]
$( derive makeFunParser ''Foo )
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Re: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
Here's the output from -ddump-splices (thanks Saizan for the tip).
It's returning a1 instead of a0.
ghci -fth -e '$( _derive_print_instance makeFunParser Foo )'
baz.hs -ddump-splices
baz.hs:1:0:
baz.hs:1:0: Splicing declarations
derive makeFunParser 'Foo
==
baz.hs:30:3-28
instance {FunParser Main.Foo} where
[]
{ parse = choice
[()
(reserved ['F', 'o', 'o'])
(()
(char '(') ((=) parse (\ a0 - ()
(char ')') (return (Main.Foo a1)] }
baz.hs:30:3: Not in scope: `a1'
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Re: [Haskell-cafe] Automatic derivation (TemplateHaskell?)
Shouldn't this work just as well? numExpr = choice [ try $ float = return . Num , integer = return . Int ] It works on Foo(10.345) but not on Bar(10, 103.34). On Apr 5, 2007, at 4:09 PM, Stefan O'Rear wrote: numExpr :: GenParser Char a NumExpr numExpr = do sg - lexeme sign nf - natOrFloat return $ either (Int . sg) (Nat . sg) nf It seems silly that there is no signed version of natOrFloat predefined, any Parsec experts? Stefan -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Which pretty printer?
Should I prefer Daan Leijen's pretty printer [1] to the Hughes-SPJ one that comes with GHC? Has anyone looked at both and is able to tell the difference? I need to pretty-print a Pascal-like language as well as C#. Thanks, Joel [1] http://www.cs.uu.nl/~daan/download/pprint/pprint.html -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Which pretty printer?
Also, are there examples of using either pretty printer? On Apr 4, 2007, at 9:57 AM, Joel Reymont wrote: Should I prefer Daan Leijen's pretty printer [1] to the Hughes-SPJ one that comes with GHC? Has anyone looked at both and is able to tell the difference? I need to pretty-print a Pascal-like language as well as C#. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] QuickCheck's co-arbitrary
Folks, I understand that arbitrary defines the possible values. How do I generally come up with co-arbitrary, though? Would someone kindly explain the choice of co-arbitrary in the following cases, specially the very last bit with variant 1 . coarbitrary a? instance Arbitrary Char where arbitrary = elements ([' ', '\n', '\0'] ++ ['a'..'h']) coarbitrary c = variant (fromEnum c `rem` 4) instance Arbitrary Ordering where arbitrary = elements [LT, EQ, GT] coarbitrary LT = variant 0 coarbitrary EQ = variant 1 coarbitrary GT = variant 2 instance Arbitrary a = Arbitrary (Maybe a) where arbitrary= frequency [ (1, return Nothing) , (3, liftM Just arbitrary) ] coarbitrary Nothing = variant 0 coarbitrary (Just a) = variant 1 . coarbitrary a Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] QuickCheck: Arbitrary for a complex type
Suppose I have a type describing a statement and that I'm trying to make it an instance of arbitrary. The type looks like this: data Statement = InputDecs [InputDecl] | VarDecs [VarDecl] | ArrayDecs [ArrayDecl] | Compound [Statement] | Assign (VarIdent, Expr) | ArrayAssign (VarIdent, [Expr], Expr) Assuming that other types involved were instances of arbitrary, how do I write arbitrary for Statement? Poking around various bits of source code I think that for a type like the following data Style = StyleValue Expr | Solid | Dashed | Dotted | Dashed2 | Dashed3 deriving Show I can write instance Arbitrary Style where arbitrary = oneOf [ StyleValue . arbitrary, elements [ Solid , Dashed , Dotted , Dashed2 , Dashed3 ] ] I'm not sure if this is correct, though, so any help is appreciated! Thanks in advance, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: QuickCheck: Arbitrary for a complex type
I got this simple example working so I think I have my question
answered.
Now I just have to learn to write generators of my own to produce
valid and invalid input for my parser.
module Foo where
import Control.Monad
import System.Random
import Test.QuickCheck
data Foo
= Foo Int
| Bar
| Baz
deriving Show
instance Arbitrary Foo where
coarbitrary = undefined
arbitrary = oneof [ return Bar
, return Baz
, liftM Foo arbitrary
]
gen' rnd = generate 1 rnd $ vector 5 :: [Foo]
gen =
do { rnd - newStdGen
; return $ gen' rnd
}
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Re: [Haskell-cafe] Re: QuickCheck: Arbitrary for a complex type
One last bit then... My identifiers should start with letter | char '_' and the tail should be alphaNum | char '_'. I guess I can use choose and oneof to produce the right set of characters but how do I combine the two into a single identifier of a given length (up to 20 chars, say)? Thanks, Joel On Apr 4, 2007, at 5:27 PM, Fawzi Mohamed wrote: Great, just one thing that could be important : when you have recursive structures (like your Statement through Compound) be sure to use sized (\mySize - ...) as generator for arbitrary so that you can avoid infinite looping. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Automatic derivation (TemplateHaskell?)
Folks,
I have very uniform Parsec code like this and I'm wondering if I can
derive it using TemplateHaskell or DrIFT or some other tool. Any ideas?
Note that
1) The reserved word matches the constructor
2) No arguments equals no parens
3) More than one argument is separated with a comma
4) For every invocation of numExpr, strExpr or boolExpr, the type of
the constructor argument is NumExpr, StrExpr and BoolExpr respectively.
This is just a handful of functions and I have to tackle about 100
more, thus my asking :-).
Thanks, Joel
---
strCall =
choice [ do { reserved NewLine
; return NewLine
}
, do { reserved GetSymbolName
; return GetSymbolName
}
, do { reserved ELDateToString
; arg1 - parens numExpr
; return $ ELDateToString arg1
}
, do { reserved TextGetString
; arg1 - parens numExpr
; return $ TextGetString arg1
}
, do { reserved Description
; return Description
}
, do { reserved GetExchangeName
; return GetExchangeName
}
, do { reserved LeftStr
; parens $ do { arg1 - strExpr
; comma
; arg2 - numExpr
; return $ LeftStr arg1 arg2
}
}
, do { reserved RightStr
; parens $ do { arg1 - strExpr
; comma
; arg2 - numExpr
; return $ RightStr arg1 arg2
}
}
, do { reserved LowerStr
; arg1 - parens strExpr
; return $ LowerStr arg1
}
, do { reserved UpperStr
; arg1 - parens strExpr
; return $ UpperStr arg1
}
, do { reserved Spaces
; arg1 - parens numExpr
; return $ Spaces arg1
}
, do { reserved SymbolRoot
; return SymbolRoot
}
, do { reserved MidStr
; parens $ do { arg1 - strExpr
; comma
; arg2 - numExpr
; comma
; arg3 - numExpr
; return $ MidStr arg1 arg2 arg3
}
}
, do { reserved NumToStr
; parens $ do { arg1 - numExpr
; comma
; arg2 - numExpr
; return $ NumToStr arg1 arg2
}
}
]
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[Haskell-cafe] SmallCheck and parser testing
Folks,
I'm trying to figure out how to test a Parsec-based parser with
Smallcheck [1]. My test AST is below and the goal is to return
StyleValue Int here if the parser is fed an integer, or return
Solid when parsing Solid, etc.
data Style
= StyleValue Expr
| Solid
| Dashed
| Dotted
| Dashed2
| Dashed3
deriving Show
I figure that the following is needed somehow:
instance Serial Style where
series = cons1 StyleValue . depth 0
\/ cons0 Solid
\/ cons0 Dashed
\/ cons0 Dashed2
\/ cons0 Dashed3
\/ cons0 Dotted
My parser is 'style', so I would be passing it as p below
run p input =
case (parse p input) of
Left err - do { putStr parse error at
; print err
}
Right x - x
How do I go from here to making sure my parser is valid?
I thought of the following property (thanks sjanssen)
prop_parse p s =
show (run p s) == s
but I don't know how to proceed from here.
Thanks, Joel
[1] http://www.cs.york.ac.uk/fp/darcs/smallcheck/
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[Haskell-cafe] Keeping a symbol table with Parsec
Folks,
Are there any examples of keeping a symbol table with Parsec?
I'm translating a parser from OCaml and I do this
OUTPUT COLON ID LP NUMERIC_SIMPLE RP
{ add $3 TypNumOut; SimpleOutputDec ($3, Number) }
Meaning that if a keyword Output is followed by : and an identifier
and then (NumericSimple) then add identifier to the symbol table as
a Number and box it in a constructor.
Then in my lexer I do a lookup to check if I have seen this
identifier and if I have seen one of type TypeNumOut I return the
token NUM instead of ID. This ensures that I can have rules with the
token NUM as opposed to ID everywhere.
How would I accomplish the same with Parsec, that is 1) update a
symbol table and 2) check identifiers and return a different token?
Thanks, Joel
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Re: [Haskell-cafe] Keeping a symbol table with Parsec
On Apr 2, 2007, at 11:17 PM, Nicolas Frisby wrote: Section 2.12 of the Parsec manual[1] discusses user state. It sounds like that is what you are after. Yes, thanks. My question is mostly about how to return a different token when the lexer finds an identifier that's already in the symbol table. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] questions about core
On Feb 12, 2007, at 5:45 AM, Matt Roberts wrote: - The hackathon videos, - A transformation-based optimiser for Haskell, - An External Representation for the GHC Core Language (DRAFT for GHC5.02), and - Secrets of the Glasgow Haskell Compiler inliner. Matt, can you please post pointers to the above? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] questions about core
On Feb 12, 2007, at 7:06 AM, Stefan O'Rear wrote: We have Core because Simon lacks the patience to solve the halting problem and properly perform effects analysis on STG. We have STG because Simon lacks the patience to wait for the 6.6 Simplifier to finish naively graph-reducing every time. Are these two different Simons? :-) -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Lambada and connecting Haskell to a Weblogic server
Yep, don't have access to the Weblogic server. I'm re-evaluating my options, though, since I'm lazy by nature. On Feb 11, 2007, at 12:30 PM, Neil Bartlett wrote: Joel, Implementing Java RMI in Haskell sounds like a nightmare. Why not use HTTP? You could easily write a wrapper Servlet that speaks XML or JSON over HTTP, and deploy that to the Weblogic server. Unless you don't have permission to deploy anything to that server for whatever reason. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Embedding ghc
Has anyone tried embedding ghc into their app? How big are the resulting binaries? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell vs Ruby as a scripting language
Is anyone using Haskell as a scripting language in their app? I'm thinking of viable it would be to embed ghc in a Mac (Cocoa) app. TextMate [1] uses Ruby as the extension language and quite successfully at that. Everybody loves Ruby since it's simple. I need a trading systems language and I'm afraid the combination of ... everything that makes Haskell otherwise great will prove a drawback in my case. What do you think? Thanks, Joel [1] http://macromates.com/ -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell vs Ruby as a scripting language
On Feb 10, 2007, at 2:25 PM, Brian Smith wrote: Is your application primarily written in Haskell? If not, you would have to create an interface between that language and Haskell in order for your Haskell programs to manipulate your domain objects and user interface. It would be Objective-C and Haskell, the exact split yet unknown. I think people would be happy if you did this because then there would be a Haskell API for Cocoa, but it seems like a lot of work. You already have this in HOC (http://hoc.sourceforge.net/) My guess is that it would be easier to do such bindings for Javascript due to its dynamic nature and it being an object-oriented language. Also, several projects have embedded Javascript successfully and so you would have many examples to base your project on. I don't see how this is different from Ruby. Visual Haskell also embeds GHC (into Visual Studio). However, Visual Haskell makes my Visual Studio unstable and often unresponsive. I'm not sure this would apply to me as I'm on Mac OSX. But, there were disadvantages too (e.g. I had to implement my own lexer because doing doing it with GHC via IPC was too slow for interactive use). Well, yes, I would want syntax highlighting and formatting. I would, in fact, need a built-in Haskell IDE. Also, I recommend looking into embedding YHC. I have not had a chance to use it yet, but it looks like it is a better fit to an interpreter-only embedding situation than GHC--with GHC, you are getting a lot more than you seem to be asking for. I would want to compile code as well. Compile bits of code 100 lines at a time and load them back into my app for execution. Does YHC compile and how efficiently? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Lambada and connecting Haskell to a Weblogic server
Folks, Where can I find Lambada these days and would it be of any use to me in trying to connect to a Weblogic server? To make the long story short, my broker's Java software connects to a remote Weblogic server and I would like to do the same. I suppose this would require me to implement Java RMI in Haskell which is non- trivial. I wonder if it would be easier for me to implement a Java server that talks to Weblogic and then connect to that server. What do you think? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Parsec and Java
Folks, Is there a Java parser implemented using Parsec? Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How did you stumble on Haskell?
I'll go for the shortest story... I stumbled upon Simon's Composing Financial Contracts paper, Simon was gracious enough to spend a fair bit of time on the phone with me. The rest is history :-). Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] A distributed and replicating native Haskell database
Folks, Allegro Common Lisp has AllegroCache [1], a database built on B-Trees that lets one store Lisp objects of any type. You can designate certain slots (object fields) as key and use them for lookup. ACL used to come bundled with the ObjectStore OODBMS for the same purpose but then adopted a native solution. AllegroCache is not distributed or replicating but supports automatic versioning. You can redefine a class and new code will store more (or less) data in the database while code that uses the old schema will merrily chug along. Erlang [2] has Mnesia [3] which lets you store any Erlang term (object). It stores records (tuples, actually) and you can also designate key fields and use them for lookup. I haven't looked into this deeply but Mnesia is built on top of DETS (Disk-based Term Storage) which most likely also uses a form of B-Trees. Mnesia is distributed and replicated in real-time. There's no automatic versioning with Mnesia but user code can be run to read old records and write new ones. Would it make sense to build a similar type of a database for Haskell? I can immediately see how versioning would be much harder as Haskell is statically typed. I would love to extend recent gains in binary serialization, though, to add indexing of records based on a designated key, distribution and real-time replication. What do you think? To stimulate discussion I would like to ask a couple of pointed questions: - How would you designate a key for a Haskell data structure? - Is the concept of a schema applicable to Haskell? Thanks, Joel [1] http://franz.com/products/allegrocache/index.lhtml [2] http://erlang.org/faq/t1.html [3] http://erlang.org/faq/x1409.html -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A distributed and replicating native Haskell database
On Feb 2, 2007, at 3:06 PM, Paul Johnson wrote: As a rule, storing functions along with data is a can of worms. Either you actually store the code as a BLOB or you store a pointer to the function in memory. Either way you run into problems when you upgrade your software and expect the stored functions to work in the new context. ACache does not store code in the database. You cannot read the database unless you have your original class code. ACache may store the schema, i.e. the parent class names, slot names, etc. Erlang also has a very disciplined approach to code updates, which presumably helps a lot when functions are stored. No storing of code here either. What you store in Erlang is just tuples so there's no schema or class definition. No functions are stored since any Erlang code can fetch the tuples from Mnesia. You do need to have the original record definition around but this is just to be able to refer to tuple elements with field names rather name field position. I very much admire Mnesia, even though I'm not an Erlang programmer. It would indeed be really cool to have something like that. But Mnesia is built on the Erlang OTP middleware. I would suggest that Haskell needs a middleware with the same sort of capabilities first. Then we can build a database on top of it. Right. That would be a prerequisite. The real headache is type safety. Erlang is entirely dynamically typed, so untyped schemas with column values looked up by name at run-time fit right in, and its up to the programmer to manage schema and code evolution to prevent errors. Doing all this in a statically type safe way is another layer of complexity and checking. I believe Lambdabot does schema evolution. Alternatively the protocol can be defined in a special purpose protocol module P, and A and B then import P. This is the approach taken by CORBA with IDL. However what happens if P is updated to P'? Does this mean that both A and B need to be recompiled and restarted simultaneously? Requiring this is a Bad Thing; imagine if every bank in the world had to upgrade and restart its computers simultaneously in order to upgrade a common protocol. I would go for the middle ground and dump the issue entirely. Lets be practical here. When a binary protocol is updated, all code using the protocol needs to be updated. This would be good enough. It would suite me just fine too as I'm not yearning for CORBA, I just want to build a trading infrastructure entirely in Haskell. There is still the possibility of a run-time failure at the protocol negotiation stage of course, if it transpires that the to processes have no common protocol. So no protocol negotiation! However there is a wrinkle here: what about pass through processes which don't interpret the data but just store and forward it. Various forms of protocol adapter fit this scenario, as does the database you originally asked about. Any packet traveling over the wire would need to have a size, followed by a body. Any pass-through protocol can just take the binary blob and re-send it. Thanks, Joel -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Connected!
What part of Russia do you live in? On Feb 1, 2007, at 1:23 PM, Bulat Ziganshin wrote: Hello haskell-cafe, i've just got ADSL connection here! it's slow (64k) and not cheap, but at least it is completely different from dial-up i've used before -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] proposal: HaBench, a Haskell Benchmark Suite
On Jan 28, 2007, at 8:51 AM, Andy Georges wrote: it is nice to know that e.g., Data.ByteString performs as good as C, but is would be even nicer to see that large, real-life apps can reach that same performance. What about using darcs as a benchmark? I heard people say it's slow. The undercurrent is that it's slow because it's written in Haskell. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
