Re: [Haskell-cafe] A first glimps on the {-# NOUPDATE #-} pragma
Hi, Am Dienstag, den 28.08.2012, 18:16 -0400 schrieb Carter Schonwald: On Tuesday, August 28, 2012, Yves Parès wrote: Monad? Simple strictness anotation is enough in that case: upd_noupd n = let l = myenum' 0 n h = head l in h `seq` last l + h darn, I though I changed my examples before posting to: upd_noupd n = let l = myenum' 0 n in last l + length l (head was a bad example because actually due to strictness analysis and worker/wrapper transformation, GHC would yield good code even without `seq`). In this case (which is actually the benchmarked case), reordering or strictness annotations do not help. Greetings and sorry for the confusion, Joachim -- Dipl.-Math. Dipl.-Inform. Joachim Breitner Wissenschaftlicher Mitarbeiter http://pp.info.uni-karlsruhe.de/~breitner signature.asc Description: This is a digitally signed message part ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] A first glimps on the {-# NOUPDATE #-} pragma
Hi,
upd_noupd n =
let l = myenum' 0 n
in last l + length l
This could be rewritten as
upd_noupd n =
let l n = myenum' 0 n
in last (l n) + length (l n)
Or a special form of let could be introduced to define locally-scoped macros:
upd_noupd n =
let# l = myenum' 0 n
in last l + length l
What's the strength of the {-# NOUPDATE #-} approach?
Regards,
Facundo
Date: Wed, 29 Aug 2012 10:20:21 +0200
From: Joachim Breitner breit...@kit.edu
Subject: Re: [Haskell-cafe] A first glimps on the {-# NOUPDATE #-}
pragma
To: haskell-cafe@haskell.org
Message-ID: 1346228421.4271.9.camel@kirk
Content-Type: text/plain; charset=iso-8859-15
Hi,
Am Dienstag, den 28.08.2012, 18:16 -0400 schrieb Carter Schonwald:
On Tuesday, August 28, 2012, Yves Par?s wrote:
Monad? Simple strictness anotation is enough in that case:
upd_noupd n =
let l = myenum' 0 n
h = head l
in h `seq` last l + h
darn, I though I changed my examples before posting to:
upd_noupd n =
let l = myenum' 0 n
in last l + length l
(head was a bad example because actually due to strictness analysis
and worker/wrapper transformation, GHC would yield good code even
without `seq`).
In this case (which is actually the benchmarked case), reordering or
strictness annotations do not help.
Greetings and sorry for the confusion,
Joachim
--
Dipl.-Math. Dipl.-Inform. Joachim Breitner
Wissenschaftlicher Mitarbeiter
http://pp.info.uni-karlsruhe.de/~breitner
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Re: [Haskell-cafe] A first glimps on the {-# NOUPDATE #-} pragma
Hi Facundo,
Am Mittwoch, den 29.08.2012, 10:26 -0300 schrieb Facundo Domínguez:
upd_noupd n =
let l = myenum' 0 n
in last l + length l
This could be rewritten as
upd_noupd n =
let l n = myenum' 0 n
in last (l n) + length (l n)
Or a special form of let could be introduced to define locally-scoped macros:
upd_noupd n =
let# l = myenum' 0 n
in last l + length l
What's the strength of the {-# NOUPDATE #-} approach?
it does not require refactoring of the code. There is not always a
parameter handy that you can use to prevent sharing, and using () for
that sometimes fails due to the full-lazyness-transformation.
And a locally-scoped macros would not help in this case:
test g n = g (myenum' 0 n)
Now you still might want to prevent the long list to be stored, but here
it cannot be done just by inlining or macro expansion.
Greetings,
Joachim
--
Dipl.-Math. Dipl.-Inform. Joachim Breitner
Wissenschaftlicher Mitarbeiter
http://pp.info.uni-karlsruhe.de/~breitner
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Re: [Haskell-cafe] A first glimps on the {-# NOUPDATE #-} pragma
And of course the biggest reason for this change, is we want GHC to continue
to become smarter. Remember, Haskell is a high level language. The
original promise, is that the code should be algebraically optimizable by
the compiler itself. Yes, of course many Haskell coders have learned to
deal with the places where Haskell is all to close to the metal. But we
hope that this will not always be the case. The interesting part, may not
be that you can add the pragma yourself, but that in the future, you won't
have to change anything at all.
Tim
-- Původní zpráva --
Od: Joachim Breitner breit...@kit.edu
Datum: 29. 8. 2012
Předmět: Re: [Haskell-cafe] A first glimps on the {-# NOUPDATE #-} pragma
Hi Facundo,
Am Mittwoch, den 29.08.2012, 10:26 -0300 schrieb Facundo Domínguez:
upd_noupd n =
let l = myenum' 0 n
in last l + length l
This could be rewritten as
upd_noupd n =
let l n = myenum' 0 n
in last (l n) + length (l n)
Or a special form of let could be introduced to define locally-scoped
macros:
upd_noupd n =
let# l = myenum' 0 n
in last l + length l
What's the strength of the {-# NOUPDATE #-} approach?
it does not require refactoring of the code. There is not always a
parameter handy that you can use to prevent sharing, and using () for
that sometimes fails due to the full-lazyness-transformation.
And a locally-scoped macros would not help in this case:
test g n = g (myenum' 0 n)
Now you still might want to prevent the long list to be stored, but here
it cannot be done just by inlining or macro expansion.
Greetings,
Joachim
--
Dipl.-Math. Dipl.-Inform. Joachim Breitner
Wissenschaftlicher Mitarbeiter
http://pp.info.uni-karlsruhe.de/~breitner
(http://pp.info.uni-karlsruhe.de/%7Ebreitner)___
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Re: [Haskell-cafe] A first glimps on the {-# NOUPDATE #-} pragma
On 29 August 2012 15:21, Joachim Breitner breit...@kit.edu wrote:
Hi Facundo,
Am Mittwoch, den 29.08.2012, 10:26 -0300 schrieb Facundo Domínguez:
upd_noupd n =
let l = myenum' 0 n
in last l + length l
This could be rewritten as
upd_noupd n =
let l n = myenum' 0 n
in last (l n) + length (l n)
Or a special form of let could be introduced to define locally-scoped
macros:
upd_noupd n =
let# l = myenum' 0 n
in last l + length l
What's the strength of the {-# NOUPDATE #-} approach?
it does not require refactoring of the code. There is not always a
parameter handy that you can use to prevent sharing, and using () for
that sometimes fails due to the full-lazyness-transformation.
And a locally-scoped macros would not help in this case:
test g n = g (myenum' 0 n)
Now you still might want to prevent the long list to be stored, but here
it cannot be done just by inlining or macro expansion.
Syntactically, I'd prefer something that looks more like a function. With
a pragma it's difficult to see what expression it actually affects. For
example, we already have the special functions lazy and inline. Since
avoiding updates essentially turns lazy evaluation into call-by-name you
could call it cbn. Perhaps that suggests a different use case, though, so
nonstrict, unshared, or nonlazy might be more self-explanatory.
I'd also like to point out that avoiding updates can dramatically improve
the kind of speedups my tracing JIT can achieve. In particular, on some
benchmarks, it can optimise idiomatic Haskell code to the same level as
stream fusion. I can simulate that by avoiding *all* updates (i.e., use
call-by-name), but that would break some programs badly. (Technically,
that's all legal, but I'm pretty sure it breaks any tying-the-knot
tricks.)
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[Haskell-cafe] ANNOUNCE: persistent-vector-0.1.0.1
I uploaded a package implementing persistent vectors using array mapped tries (based on the implementation in clojure). Version 0.1.0.0 was broken, so I am starting off with 0.1.0.1. http://hackage.haskell.org/package/persistent-vector Persistent vectors are a sequence container offering efficient and purely functional append (snoc), indexing, and updates. This is similar to Data.Sequence from containers. The array mapped trie is closely related to the data structure used in the unordered-containers package. Comparison to Sequence: * Faster indexing and append * Slightly slower updates to existing elements * O(1) slicing * Sequence offers efficient prepend and concatenate (persistent-vector does not implement prepend, while concatenate is O(n)). I tried to model the API after Sequence as much as was reasonable, but a few functions are still missing. Some are reasonable to implement and some would be difficult to make efficient. The results from criterion (mostly comparing against Sequence and IntMap) are posted here: http://pages.cs.wisc.edu/~travitch/pvec.html The *Vec* runs are the vectors from this package and IM and Seq are IntMap and Sequence from containers. Hopefully someone will find this useful. Comments and suggestions are definitely welcome for anything: API, implementation, test suite, or benchmarks. pgpGGufATcanJ.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: persistent-vector-0.1.0.1
Where the persistent part of the name comes from?. It can be serialized/deserialized from a persistent storage automatically or on demand? 2012/8/29 Tristan Ravitch travi...@cs.wisc.edu I uploaded a package implementing persistent vectors using array mapped tries (based on the implementation in clojure). Version 0.1.0.0 was broken, so I am starting off with 0.1.0.1. http://hackage.haskell.org/package/persistent-vector Persistent vectors are a sequence container offering efficient and purely functional append (snoc), indexing, and updates. This is similar to Data.Sequence from containers. The array mapped trie is closely related to the data structure used in the unordered-containers package. Comparison to Sequence: * Faster indexing and append * Slightly slower updates to existing elements * O(1) slicing * Sequence offers efficient prepend and concatenate (persistent-vector does not implement prepend, while concatenate is O(n)). I tried to model the API after Sequence as much as was reasonable, but a few functions are still missing. Some are reasonable to implement and some would be difficult to make efficient. The results from criterion (mostly comparing against Sequence and IntMap) are posted here: http://pages.cs.wisc.edu/~travitch/pvec.html The *Vec* runs are the vectors from this package and IM and Seq are IntMap and Sequence from containers. Hopefully someone will find this useful. Comments and suggestions are definitely welcome for anything: API, implementation, test suite, or benchmarks. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: persistent-vector-0.1.0.1
On Wed, Aug 29, 2012 at 10:13 AM, Alberto G. Corona agocor...@gmail.com wrote: Where the persistent part of the name comes from?. It can be serialized/deserialized from a persistent storage automatically or on demand? Persistent have two meanings unfortunately. In functional programming it's used to mean that every operation on a data structure preserves the old version as well. -- Johan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANNOUNCE: persistent-vector-0.1.0.1
Sorry, persistent as in purely functional. Updates to one vector don't affect others. I guess the distinction isn't as useful in Haskell as it is in other languages since it is the default. On Wed, Aug 29, 2012 at 07:13:38PM +0200, Alberto G. Corona wrote: Where the persistent part of the name comes from?. It can be serialized/deserialized from a persistent storage automatically or on demand? 2012/8/29 Tristan Ravitch travi...@cs.wisc.edu I uploaded a package implementing persistent vectors using array mapped tries (based on the implementation in clojure). Version 0.1.0.0 was broken, so I am starting off with 0.1.0.1. http://hackage.haskell.org/package/persistent-vector Persistent vectors are a sequence container offering efficient and purely functional append (snoc), indexing, and updates. This is similar to Data.Sequence from containers. The array mapped trie is closely related to the data structure used in the unordered-containers package. Comparison to Sequence: * Faster indexing and append * Slightly slower updates to existing elements * O(1) slicing * Sequence offers efficient prepend and concatenate (persistent-vector does not implement prepend, while concatenate is O(n)). I tried to model the API after Sequence as much as was reasonable, but a few functions are still missing. Some are reasonable to implement and some would be difficult to make efficient. The results from criterion (mostly comparing against Sequence and IntMap) are posted here: http://pages.cs.wisc.edu/~travitch/pvec.html The *Vec* runs are the vectors from this package and IM and Seq are IntMap and Sequence from containers. Hopefully someone will find this useful. Comments and suggestions are definitely welcome for anything: API, implementation, test suite, or benchmarks. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe pgpyRTf9uZFKs.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Darcs fetches too little files
Albert Einstein said: Insanity: doing the same thing over and over again and expecting different results. I repeated the command today and it worked! So, did you expect the result to be different, or did you re-try just to confirm that it doesn't work? Stefan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Darcs fetches too little files
On Wed, 29 Aug 2012 23:10:24 +0200, Stefan Monnier monn...@iro.umontreal.ca wrote: Albert Einstein said: Insanity: doing the same thing over and over again and expecting different results. I repeated the command today and it worked! So, did you expect the result to be different, or did you re-try just to confirm that it doesn't work? The day after I tried the command the first time, I thought the result might be different; I have the experience that my browser crashes, and starting it again results in an immediate crash. Logging off and on again solves the problem. This might be because of a corrupted DLL or a corrupted data area of a DLL. The command failure could have also been caused by a problem at the server side. In conclusion: repeating the same thing could give different results. Regards, Henk-Jan van Tuyl -- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html Haskell programming -- ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Iterations (Was: Re: Darcs fetches too little files)
Le 29/08/2012 23:55, Henk-Jan van Tuyl a écrit : In conclusion: repeating the same thing could give different results. Certainly! My favourite example is : sex. Jerzy Karczmarczuk ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Weekly News: Issue 242
Welcome to issue 242 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of August 19 to 25, 2012. Quotes of the Week * srhb: I think that's going into space rather than diving into the deep end. * edwardk: normally i don't bother with little things like documentation, benchmarks and tests, but I recently discovered that when I do, I get these curious things called users. * shachaf: Number of comonads released by edwardk will exceed the number of words in the English language by 2015, experts report. Top Reddit Stories * Hackage2 server ready for testing Domain: haskell.org, Score: 75, Comments: 16 On Reddit: [1] http://goo.gl/WTebL Original: [2] http://goo.gl/dHkGo * Monads In Pictures Domain: newartisans.com, Score: 60, Comments: 24 On Reddit: [3] http://goo.gl/QMfGv Original: [4] http://goo.gl/ycmvx * A new fast and easy to use CSV library Domain: blog.johantibell.com, Score: 53, Comments: 26 On Reddit: [5] http://goo.gl/eRKSm Original: [6] http://goo.gl/uRmfz * duckduckgo.com just became my favorite search engine due to haskell support Domain: self.haskell, Score: 50, Comments: 14 On Reddit: [7] http://goo.gl/1tBCg Original: [8] http://goo.gl/1tBCg * An example on how ridiculously powerful haskells type system is Domain: chrisdone.com, Score: 44, Comments: 61 On Reddit: [9] http://goo.gl/iwJT2 Original: [10] http://goo.gl/NovM7 * Galois Internship Available: Come build high-assurance autonomous vehicles! Domain: corp.galois.com, Score: 43, Comments: 13 On Reddit: [11] http://goo.gl/iJEih Original: [12] http://goo.gl/8ckL4 * Issue 20 « The Monad.Reader Domain: themonadreader.wordpress.com, Score: 34, Comments: 8 On Reddit: [13] http://goo.gl/K5Cc7 Original: [14] http://goo.gl/dBSdK * Functional Game Design: Making Pong in Elm Domain: elm-lang.org, Score: 29, Comments: 11 On Reddit: [15] http://goo.gl/sCdfE Original: [16] http://goo.gl/RL2i1 * Making HaskellDB slightly more type-safe Domain: chrisdone.com, Score: 28, Comments: 3 On Reddit: [17] http://goo.gl/b16v5 Original: [18] http://goo.gl/7v38l * Identifying outdated packages in cabal install plans Domain: byorgey.wordpress.com, Score: 24, Comments: 5 On Reddit: [19] http://goo.gl/4yTrR Original: [20] http://goo.gl/Zjw7b * ghcLiVE project escapes! Domain: ghclive.wordpress.com, Score: 23, Comments: 16 On Reddit: [21] http://goo.gl/IiXaA Original: [22] http://goo.gl/QzUHW * My view on why relational algebra matters Domain: users.utu.fi, Score: 22, Comments: 16 On Reddit: [23] http://goo.gl/byYZW Original: [24] http://goo.gl/3NSmI * ANN basic-prelude 0.3 (now comes with a fully-featured Prelude replacement) Domain: haskell.org, Score: 21, Comments: On Reddit: [25] http://goo.gl/klUAO Original: [26] http://goo.gl/4Ccyv * I just realized that running monads is applying a left monad action Domain: self.haskell, Score: 21, Comments: 53 On Reddit: [27] http://goo.gl/Geus4 Original: [28] http://goo.gl/Geus4 * You can soon play in the cabal sandbox Domain: blog.johantibell.com, Score: 20, Comments: 10 On Reddit: [29] http://goo.gl/QuVo0 Original: [30] http://goo.gl/6Q9a9 * Unordered tuples and type algebra Domain: byorgey.wordpress.com, Score: 18, Comments: 3 On Reddit: [31] http://goo.gl/N8iuz Original: [32] http://goo.gl/8l11g * Haskell-Type-Exts Passed the Final Evaluation Domain: cleantypecheck.wordpress.com, Score: 16, Comments: 3 On Reddit: [33] http://goo.gl/ok7CL Original: [34] http://goo.gl/ttsFb * LambdaJam Conference (from the creator of Strange Loop) -- Coming to Chicago in Summer 2013! Domain: lambdajam.com, Score: 15, Comments: On Reddit: [35] http://goo.gl/ytWNE Original: [36] http://goo.gl/ziyYc * Hello world in SKI combinator calculus Domain: self.haskell, Score: 14, Comments: 16 On Reddit: [37] http://goo.gl/qVDMw Original: [38] http://goo.gl/qVDMw * Is this Monoid instance in the standard library somewhere? Domain: self.haskell, Score: 14, Comments: 7 On Reddit: [39] http://goo.gl/cFHG7 Original: [40] http://goo.gl/cFHG7 * Applicative functors: definition and syntax (a reply) Domain: tomasp.net, Score: 13, Comments: 7 On Reddit: [41] http://goo.gl/4VPKR Original: [42] http://goo.gl/saU2j Top StackOverflow Questions * Lazy Evaluation and Time Complexity votes: 40, answers: 7 Read on SO: [43] http://goo.gl/f9QTO * What is the purpose of Rank2Types? votes: 21, answers: 3 Read on SO: [44] http://goo.gl/XrPHP * “Modern” HList? votes: 16, answers: 1 Read
[Haskell-cafe] Build regressions due to GHC 7.6
Since the release of the GHC 7.6 RC, I've been going through my packages and fixing up build problems so that people who upgrade to 7.6 will have a smooth ride. Sad to say, my experience of 7.6 is that it has felt like a particularly rough release for backwards incompatibility. I wanted to quantify the pain, so I did some research, and here's what I found. I maintain 25 open source Haskell packages. Of these, the majority have needed updates due to the GHC 7.6 release: - base16-bytestring - blaze-textual - bloomfilter - configurator - criterion - double-conversion - filemanip - HDBC-mysql - mwc-random - pcap - pool - riak-haskell-client - snappy - text - text-format - text-icu That's 16 out of 25 packages I've had to update. I've also either reported bugs on, or had to fix, several other people's packages along the way (maybe four?). So let's say I've run into problems with 20 out of the combined 29 packages of mine and my upstreams. The reasons for these problems fall into three bins: - Prelude no longer exports catch, so a lot of import Prelude hiding (catch) had to change. - The FFI now requires constructors to be visible, so CInt has to be imported as CInt(..). - bytestring finally got bumped to 0.10, so many upper bounds had to be relaxed (*cf* my suggestion that the upper-bounds-by-default policy is destructive). It has been a lot of work to test 29 packages, and then modify, rebuild, and release 20 of them. It has consumed most of my limited free time for almost two weeks. Worse, this has felt like make-work, of no practical benefit to anyone beyond scrambling to restore the status quo ante. If over half of my packages needed fixing, I'm alarmed at the thought of the effects on the rest of Hackage. I'm torn over this. I understand and agree with the impetus to improve the platform by tidying things up, and yet just two seemingly innocuous changes (catch and FFI) have forced me to do a bunch of running to stand still. I don't have any suggestions about what to do; I know that it's hard to estimate the downstream effects of what look like small changes. And so I'm not exactly complaining. Call this an unhappy data point. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
