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Core libraries

glasgow-user - Fri, 10/16/2015 - 9:21am
Hello GHC users, For various reasons i'm trying to package something which is compatible with/equivalent to the Haskell Platform. I've been looking at the list posted at [0], and it turns out that GHC 7.10.2 doesn't bundle all the packages that are promised. (Or it's a case of PEBKAC and i apologise!) When i do `ghc-pkg list`, the output under ../package.conf.d provided by GHC notably has the following differences with the website list: $ diff website-list <(ghc-pkg list | ..prettify..) 2a3,4 10c12,14 < haddock --- 12,13c16 < old-locale < old-time --- 15a19 16a21 What surprises me is the lack of haddock, old-time and old-locale. Is this intentional, or a glitch on the website? I notice that these "missing" libraries are repeated in the `Additional Platform Libraries' and `Programs and Tools' sections. I guess this means that as a GHC packager, i should add these items separately? I guess what i'm saying is that i believe there is a bug in that list [0], but i'm not sure enough that i understand the
Categories: Offsite Discussion

Default definition for fromRational

libraries list - Thu, 10/15/2015 - 11:51pm
A suitable default definition for fromRational could be the following: fromRational n = fromInteger (numerator n) / fromInteger (denominator n) Changing the MINIMUM pragma to just {-# MINIMAL recip | (/) #-} - Joe
Categories: Offsite Discussion

Handling multiple fds with GHC

glasgow-user - Wed, 10/07/2015 - 8:49am
Hi, the last few days, I tried to get an IO-Event system running with GHC i.e. trigger an IO action when there is data to read from a fd. I looked at a few different implementations, but all of them have some downside. * using select package - This uses the select syscall. select is rather limited (fd cannot be * using GHC.Event - GHC.Event is broken in 7.10.1 (unless unsafeCoerce and a hacky trick are used) - GHC.Event is GHC internal according to hackage - Both Network libraries I looked at (networking (Network.Socket) and socket (System.Socket)) crash the application with GHC.Event - with 7.8+ I didn't see a way to create your own EventManager, so it only works with -threaded * using forkIO and threadWaitRead for each fd in a loop - needs some kind of custom control structure around it - uses a separate thread for each fd - might become pretty awkward to handle multiple events * using poll package - blocks in a safe foreign call - needs some kind of wrapper Fro
Categories: Offsite Discussion

using nmitchell's space leak detection technique

glasgow-user - Fri, 10/02/2015 - 3:02am
Neil Mitchell wrote an article about finding space leaks by limiting the stack size: I'm giving it a try, but the results don't make any sense to me. My understanding is that the too-deep stack indicates that someone created too many thunks, so when they get evaluated you have to descend too many times. And if the stack trace seems to be a reasonable size (say 100 stack frames somehow consuming 1mb of stack) then it means there is a recursive call in there somewhere that ghc is helpfully eliding. And lastly, that the thing about "Stack space overflow: current size 33568 bytes." always showing 33568 bytes is due to a ghc bug and it should actually be whatever limit I gave it. Is all this accurate? The stack trace jumps around a lot, to places which are not lexically present in the caller. I assume this is just lazy evaluation, so e.g. maybe 'f' doesn't call 'g', but if 'f' forces a value returned from 'g' which has not yet been forced,
Categories: Offsite Discussion

New gtk2hs 0.12.4 release

gtk2hs - Wed, 11/21/2012 - 12:56pm

Thanks to John Lato and Duncan Coutts for the latest bugfix release! The latest packages should be buildable on GHC 7.6, and the cairo package should behave a bit nicer in ghci on Windows. Thanks to all!


Categories: Incoming News