- Glasgow-haskell-users

SIMD
by Dominic Steinitz 13 Apr '15

13 Apr '15

What’s the story with this? I tried to follow the instructions here: https://ghc.haskell.org/trac/ghc/wiki/SIMD <https://ghc.haskell.org/trac/ghc/wiki/SIMD> but I get > ~ $ git clone -b simd http://git.haskell.org/ghc.git > Cloning into 'ghc'... > fatal: Remote branch simd not found in upstream origin Dominic Steinitz dominic(a)steinitz.org http://idontgetoutmuch.wordpress.com

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acrisciu@gmail.com has indicated you're a friend. Accept?
by acrisciu＠gmail.com 09 Apr '15

09 Apr '15

Hi, acrisciu(a)gmail.com wants to follow you. ****** Is acrisciu(a)gmail.com you friend? ****** If Yes please follow the link below: http://invites.infoaxe.net/signup_e.html?fullname=&email=glasgow-haskel… If No please follow the link below: http://invites.infoaxe.net/signup_e.html?fullname=&email=glasgow-haskel… Follow the link below to remove yourself from all such emails http://invites.infoaxe.net/uns_inviter.jsp?email=glasgow-haskell-users@hask…

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Typed splices and type checking
by J. Garrett Morris 08 Apr '15

08 Apr '15

Hello, I've run into another misunderstanding with Template Haskell and typed splices. For example, I was hoping to use typed splices to generate earlier errors from Printf. Here's the world's least handy printf: > class Printf t > where printf :: String -> Q (TExp String) -> Q (TExp t) > > instance Printf String > where printf s t | '%' `notElem` s = [|| $$t ++ s ||] > | otherwise = fail ("Unexpected format %" > ++ [c]) > where (_, _:c:_) = break ('%' ==) s > > instance Printf t => Printf (Char -> t) > where printf s t > | c /= 'c' = fail ("Unexpected format %" ++ [c] ++ > " for character") > | otherwise = [|| \c -> $$(printf s'' > [|| $$t ++ s' ++ [c] ||]) > ||] > where (s', '%':c:s'') = break ('%' ==) s Now, consider these two definitions: > f :: Char -> String > f = $$(printf "foo %c" [||""||]) > h :: Char -> String > h y = $$(printf "foo %c" [||""||]) y I would have expected these to be equivalent, from a type checking perspective. However, while the first types fine, the second generates the error message: > Printing.hs:14:12: > No instance for (Printf t0) arising from a use of `printf' > The type variable `t0' is ambiguous > Note: there are several potential instances: > instance Printf t => Printf (Char -> t) > -- Defined at Printf.hs:20:10 > instance Printf String -- Defined at Printf.hs:9:10 > In the expression: printf "foo %c" [|| "" ||] > In the Template Haskell splice > $$(printf "foo %c" [|| "" ||]) > In the expression: $$(printf "foo %c" [|| "" ||]) Should I have anticipated this? Ought the interaction of typed splices and eta-expansion be problematic? /g -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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runghc and GhcWithInterpreter
by Jeremy 07 Apr '15

07 Apr '15

I've built GHC with GhcWithInterpreter = NO. runghc is built and installed, but errors out with "not built for interactive use". Is runghc supposed to work with such a build? If not, why is it built at all? -- View this message in context: http://haskell.1045720.n5.nabble.com/runghc-and-GhcWithInterpreter-tp576832… Sent from the Haskell - Glasgow-haskell-users mailing list archive at Nabble.com.

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Binary bloat in 7.10
by Jeremy 07 Apr '15

07 Apr '15

Why do the 7.10 libraries take up so much more space than 7.8? For example, using the same build options and strip --strip-unneeded, 7.8 leaves me with 15M libHSCabal-1.18.1.5.a 17M HSCabal-1.18.1.5.o whereas 7.10 balloons to 23M HSCabal-1.22.2.0-HWT8QvVfJLn2ubvobpycJY.o 53M libHSCabal-1.22.2.0-HWT8QvVfJLn2ubvobpycJY.a -- View this message in context: http://haskell.1045720.n5.nabble.com/Binary-bloat-in-7-10-tp5768067.html Sent from the Haskell - Glasgow-haskell-users mailing list archive at Nabble.com.

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skip hpc during build
by Jeremy 06 Apr '15

06 Apr '15

I'm deleting hpc after building ghc for a vm to save space. Is there an easy way to skip building it in the first place? -- View this message in context: http://haskell.1045720.n5.nabble.com/skip-hpc-during-build-tp5768327.html Sent from the Haskell - Glasgow-haskell-users mailing list archive at Nabble.com.

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Functional dependencies conflict
by Daniel Trstenjak 05 Apr '15

05 Apr '15

Hi, I'm getting the compile error: Gamgine/Image/PNG/Internal/Parser.hs:14:10: Functional dependencies conflict between instance declarations: instance Monad m => Stream LB.ByteString m Word8 -- Defined at Gamgine/Image/PNG/Internal/Parser.hs:14:10 instance Monad m => Stream LB.ByteString m Char -- Defined in ‘Text.Parsec.Prim’ The relevant stuff from the parsec 3.1.9 code[1] is: {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleContexts, UndecidableInstances #-} ... import qualified Data.ByteString.Lazy.Char8 as CL import qualified Data.ByteString.Char8 as C ... class (Monad m) => Stream s m t | s -> t where uncons :: s -> m (Maybe (t,s)) instance (Monad m) => Stream CL.ByteString m Char where uncons = return . CL.uncons instance (Monad m) => Stream C.ByteString m Char where uncons = return . C.uncons And from my code[2] is: {-# LANGUAGE BangPatterns, FlexibleInstances, MultiParamTypeClasses, FlexibleContexts #-} ... import qualified Data.ByteString.Lazy as LB ... instance (Monad m) => Stream LB.ByteString m Word8 where uncons = return . LB.uncons As you can see, the instances are for different ByteString types, therefore I don't quite get where GHC sees here any conflicts. Greetings, Daniel [1] https://github.com/aslatter/parsec/blob/master/Text/Parsec/Prim.hs [2] https://github.com/dan-t/Gamgine/blob/master/Gamgine/Image/PNG/Internal/Par…

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Re: [Haskell-cafe] Functional dependencies conflict
by Roman Cheplyaka 05 Apr '15

05 Apr '15

To be precise, the sets of instances differ. Eg. the Char8 module exports the IsString instance, which normal Data.ByteString.Lazy doesn't. On 05/04/15 15:25, Ivan Lazar Miljenovic wrote: > On 5 April 2015 at 22:25, Roman Cheplyaka <roma(a)ro-che.info> wrote: >> Data.ByteString.Lazy.Char8 exports the same lazy bytestring type as >> Data.ByteString.Lazy. Only functions and instances differ. > > Well, *instances* can't differ... > >> >> On 05/04/15 15:19, Daniel Trstenjak wrote: >>> >>> Hi, >>> >>> I'm getting the compile error: >>> >>> Gamgine/Image/PNG/Internal/Parser.hs:14:10: >>> Functional dependencies conflict between instance declarations: >>> instance Monad m => Stream LB.ByteString m Word8 >>> -- Defined at Gamgine/Image/PNG/Internal/Parser.hs:14:10 >>> instance Monad m => Stream LB.ByteString m Char >>> -- Defined in ‘Text.Parsec.Prim’ >>> >>> >>> >>> The relevant stuff from the parsec 3.1.9 code[1] is: >>> >>> {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleContexts, UndecidableInstances #-} >>> >>> ... >>> >>> import qualified Data.ByteString.Lazy.Char8 as CL >>> import qualified Data.ByteString.Char8 as C >>> >>> ... >>> >>> class (Monad m) => Stream s m t | s -> t where >>> uncons :: s -> m (Maybe (t,s)) >>> >>> instance (Monad m) => Stream CL.ByteString m Char where >>> uncons = return . CL.uncons >>> >>> instance (Monad m) => Stream C.ByteString m Char where >>> uncons = return . C.uncons >>> >>> >>> >>> And from my code[2] is: >>> >>> {-# LANGUAGE BangPatterns, FlexibleInstances, MultiParamTypeClasses, FlexibleContexts #-} >>> >>> ... >>> >>> import qualified Data.ByteString.Lazy as LB >>> >>> ... >>> >>> instance (Monad m) => Stream LB.ByteString m Word8 where >>> uncons = return . LB.uncons >>> >>> >>> >>> As you can see, the instances are for different ByteString types, >>> therefore I don't quite get where GHC sees here any conflicts. >>> >>> >>> Greetings, >>> Daniel >>> >>> >>> [1] https://github.com/aslatter/parsec/blob/master/Text/Parsec/Prim.hs >>> [2] https://github.com/dan-t/Gamgine/blob/master/Gamgine/Image/PNG/Internal/Par… >>> _______________________________________________ >>> Haskell-Cafe mailing list >>> Haskell-Cafe(a)haskell.org >>> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe >>> >> >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe > > >

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Help wanted: working on the GHC webpage
by Austin Seipp 03 Apr '15

03 Apr '15

Hello *, For a while now, I've been wanting to do a facelift on the GHC homepage, but among many other things it's been a low priority. I'd like for people to help, so I've tried to get the ball rolling. The webpages existed in a Darcs repository previously (which wasn't available online), but earlier today I converted them to a git repository which you can find here: https://github.com/haskell-infra/ghc-homepage The site is currently composed of a set of "server side include" files that have a crude form of HTML templating. So it's mostly just pretty verbose to add or refactor anything, and the sites templating and styling is quite old (it dates back at least 10 years!) So, I'm making an official call for some help. At the very least, I'd like to at least end up converting the site to something like Hakyll which is doable without me causing a lot of damage to the stylesheets, but for the actual page itself I'd really appreciate it if anyone could help out! Please send pull requests or file issues, it's much appreciated. -- Regards, Austin Seipp, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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immortal profiling
by Mark Wotton 03 Apr '15

03 Apr '15

https://ghc.haskell.org/trac/ghc/ticket/10235#ticket Would be really useful to be able to profile code without dying, especially in the context of a long-lived server. Am I missing something that would allow me to do this? cheers mark

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