- If we permit overlapping instances extension, then a few lines of code
decide equality for all existing and future types:
class TypeEq x y b | x y - b
instance TypeEq x x HTrue
instance TypeCast HFalse b = TypeEq x y b
This is exactly what I was after, but
| Simon (aka Dumbledore) is speaking to four different Houses: scientists
| (Ravenclaw), engineers (Hufflepuff), entrepreneurs (Slytherin), and
| managers (Griffindor).
I wish I could live up to this image!
Lots of interesting ideas on this thread, and Haskell-Cafe threads are
*supposed* to
[Redirecting to Haskell Cafe]
Hi Greg
I think it's very likely that you *can* do what you want. I have not taken
long enough to understand just what you are trying to do, but I do know why
your program is failing, and I think you'll agree it *should* fail. Look at
these lines (slightly
On Wed, 2007-04-18 at 21:12 -0700, David Roundy wrote:
On Thu, Apr 19, 2007 at 10:20:21AM +1000, Duncan Coutts wrote:
and people will for ever be defining newtype wrappers or complaining
that the whole library isn't parametrised by the endianness or whatever.
For existing formats you need
Hi!
On 4/18/07, Juan Carlos Arevalo Baeza [EMAIL PROTECTED] wrote:
This evaluates all the elements of the list using parMap (the expensive
part, right?), and then sequentially applies the action on the current
thread.
True. But currently I have the main function I would like to
parallel
G'day all.
Quoting Simon Peyton-Jones [EMAIL PROTECTED]:
Lots of interesting ideas on this thread, and Haskell-Cafe threads are
*supposed* to wander a bit. But, just to remind you all: I'm particularly
interested in
concrete examples (pref running code) of programs that are
*
* small
* useful
* demonstrate Haskell's power
* preferably something that might be a bit
tricky in another language
Something I like: A finite (binary) relation
data Rel q = Rel { elems :: [(q,q)] }
We do not export constructors, hence
rel xs =
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
[EMAIL PROTECTED] wrote:
I updated the diff example a bit:
http://andrew.bromage.org/darcs/diff/
It now features TWO newtype synonyms. This illustrates a crucial feature
of Haskell: Abstractions are cheap.
Okay, looking at that code:
The
Hi,
Just a comment or two on the implications of converting higher-order
functions to data.
The paper you reference about this uses the method of
defunctionalization. This is a whole program transformation and might
therefore not be suitable in a compiler such as GHC or YHC. On the
other hand,
Duncan Coutts wrote:
Yeah, we've concentrated so far on the serialisation of Haskell values,
not reading/writing externally defined binary formats. I don't think
we've been especially clear on that. But we do intend to tackle both.
Speaking for myself, I certainly didn't realise you were
On Thu, 2007-04-19 at 12:23 +0100, Jules Bean wrote:
Duncan Coutts wrote:
Yeah, we've concentrated so far on the serialisation of Haskell values,
not reading/writing externally defined binary formats. I don't think
we've been especially clear on that. But we do intend to tackle both.
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
Hi
isBool x = isLT x || isGT x
isNum x = not $ isBool x
isLT and isGT can be derived automatically using derve [1], with the
Is class (or DrIFT if you want).
Thanks
Neil
[1] google data derive
On 4/19/07, Joel Reymont [EMAIL PROTECTED] wrote:
Support I want to infer the type given an Op
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
Neil Mitchell wrote:
Hi
isBool x = isLT x || isGT x
isNum x = not $ isBool x
isLT and isGT can be derived automatically using derve [1], with the
Is class (or DrIFT if you want).
You can also get a long way with GHC's built in derivations for Eq, Enum
and Show.
If an Enum instance is
Joel Reymont wrote:
This is what want. Notice the succinctness.
# let infer = function | A | B | C - true; | D | E | F - false;;
val infer : foo - bool = fun
Yes, I appreciate what you want, and I know ocaml too :)
I was just talking around the other ways you can achieve it. I don't
Hi Jules,
What this leads us towards is that it might be rather nice (perhaps even
nice enough to build into a compiler) to be able to derive, for each
type with multiple constructors, a type 'which is the enumeration of the
constructors'. I.e. a type with the same constructors (up to some
a)
After filtering the content I want to use how do I extract the text?
eg
a = xtract html/body/h2/-
which should return the text contained in the h2 tag.
There is a parser called text which returns the text but I don't know
how to use it ? Is there a much simpler way I have missed?
Joel Reymont [EMAIL PROTECTED] writes:
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
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
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
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
or similar? I would agree that it's a shame one cannot just write
data Op = Aop (Minus |
Hi everybody,
I was wondering if someone had fftw bindings for haskell, or if I should
roll my own.
I did a small search but found nothing.
Fawzi
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All,
I'm interested in automating Excel using Haskell. I'm writing a little
program for my wife and it'd be nice to fill out an Excel spreadsheet for
her (with formatting so I don't think CSV will cut it). A bit of Googling
didn't turn up anything interesting.
Has any work been done on using
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 ::
On Thu, Apr 19, 2007 at 05:37:05PM +0200, Fawzi Mohamed wrote:
I was wondering if someone had fftw bindings for haskell, or if I should
roll my own.
Not that I'm aware of, but if you roll your own, please make them public,
as I'll be interested in fftw bindings before long.
--
David Roundy
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
Joel Reymont wrote:
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
On Thu, Apr 19, 2007 at 08:59:17AM -0700, Justin Bailey wrote:
All,
I'm interested in automating Excel using Haskell. I'm writing a little
program for my wife and it'd be nice to fill out an Excel spreadsheet
for her (with formatting so I don't think CSV will cut it). A bit of
On 19/04/07, Marc Weber [EMAIL PROTECTED] wrote:
There is only one library: hdirect. But I don't know its status there
have been some posts and some authors may have chnaged it.
I'd suggest grepping some mailinglist archives (you can find them all on
haskell.org) or wait till someone else gives
Hi
I'm interested in automating Excel using Haskell. I'm writing a little
program for my wife and it'd be nice to fill out an Excel spreadsheet
for her (with formatting so I don't think CSV will cut it). A bit of
Googling didn't turn up anything interesting.
Does she need to
Hi
If you application will be only small you'll be faster using VBScript.
Or Python or Perl, or (probably, I'm not sure) Ruby. Or likely many others.
No, VBA only. VBA is integrated with Excel and can talk to all the
Excel data structures, be developed inside the Excel program etc. It
can
On Thu, Apr 19, 2007 at 06:18:24PM +0100, Neil Mitchell wrote:
No, VBA only.
I had VBA in mind but typed the wrong name.
Thanks Neil for correcting my statement.
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Simon Peyton-Jones simonpj at microsoft.com writes:
But, just to remind you all: I'm particularly interested in
concrete examples (pref running code) of programs that are
* small
* useful
* demonstrate Haskell's power
* preferably something that might be a
On Thu, Apr 19, 2007 at 09:20:36 -0700, David Roundy wrote:
On Thu, Apr 19, 2007 at 05:37:05PM +0200, Fawzi Mohamed wrote:
I was wondering if someone had fftw bindings for haskell, or if I should
roll my own.
Not that I'm aware of, but if you roll your own, please make them
public, as I'll be
Magnus Therning wrote:
On Thu, Apr 19, 2007 at 09:20:36 -0700, David Roundy wrote:
On Thu, Apr 19, 2007 at 05:37:05PM +0200, Fawzi Mohamed wrote:
I was wondering if someone had fftw bindings for haskell, or if I should
roll my own.
Not that I'm aware of, but if you roll your own, please make
A theorem prover might be a really cool example, but if there's one
person in the audience that cares then Simon is lucky. :) You need
to have examples that people can recognize and see the utility of.
-- Lennart
On Apr 19, 2007, at 20:48 , DavidA wrote:
Simon Peyton-Jones
G'day all.
Quoting Isaac Dupree [EMAIL PROTECTED]:
Okay, looking at that code:
The comments before the type definitions are mostly good...
now it looks like I'm going into critique mode :)
BTW, for the record, I didn't try too hard with this. It is meant
to be illustrative of what you can
On Thu, Apr 19, 2007 at 05:46:49PM -0400, Al Falloon wrote:
For us less knowledgable, what's fftw?
Fastest Fourier Transform in the West. http://www.fftw.org/
Its cool, they use generative programming: an OCaml program generates
codlets in C that can be composed and tuned to the specifics
I hate to recommend Java to Haskellers, but there is a project named
Poi at Apache's Jakarta site[1] that will allow you to (with some Java
programming) read, write, and manipulate Excel files directly. You
don't have to COM to Excel, you don't even need Excel installed! Nice
for producing
There are also equivalent libraries (for producing xls files without
excel) for
python: http://sourceforge.net/projects/pyexcelerator
http://sourceforge.net/projects/pyxlwriter/
perl: http://search.cpan.org/dist/Spreadsheet-WriteExcel/
so you don't have to use java...
Tim
-Original
DavidA wrote:
Simon Peyton-Jones simonpj at microsoft.com writes:
But, just to remind you all: I'm particularly interested in
concrete examples (pref running code) of programs that are
* small
* useful
* demonstrate Haskell's power
* preferably something that
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