- Glasgow-haskell-users

recompilation on --main-is
by Conrad Parker 17 Feb '12

17 Feb '12

Hi, We have a project with around 200 Haskell source files, and around 20 executables which import these (as well as importing third-party libraries). We first build all the non-main files using a makefile generated with ghc -M. We then build the executables using a separate invocation of "ghc --make --main-is foo.hs", for each foo.hs. This worked fine with ghc-7.2.1; each final "ghc --make" would simply link the pre-built object files -- but with ghc-7.4.1 all these files are recompiled for each target executable. As a result our full build takes around 10-20x longer with ghc-7.4.1 than ghc-7.2.1. Looking at compiler/iface/FlagChecker.hs, it seems that the --main-is flag is used as an input to the recompilation checker. It would make sense that --main-is should force recompilation of the particular file that exports 'main', but it also forces recompilation of its dependencies. Is this a bug or is there a good reason to recompile everything? Conrad.

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ANNOUNCE: GHC 7.4.1 Release Candidate 2
by Ian Lynagh 15 Feb '12

15 Feb '12

We are pleased to announce the first release candidate for GHC 7.4.1: http://www.haskell.org/ghc/dist/7.4.1-rc2/ This includes the source tarball, installers for OS X and Windows, and bindists for amd64/Linux, i386/Linux, amd64/FreeBSD and i386/FreeBSD. Please test as much as possible; bugs are much cheaper if we find them before the release! We expect this to be the last release candidate, with the final release in approximately 1 week's time. Thanks Ian, on behalf of the GHC team

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Re: Changes to Typeable
by Iavor Diatchki 14 Feb '12

14 Feb '12

Hello, On Mon, Feb 13, 2012 at 5:32 PM, Edward Kmett <ekmett(a)gmail.com> wrote: > > There are fewer combinators from commonly used classes for working with > the left argument of a bifunctor, however. > I think that the bifunctor part of Bas's version is a bit of a red herring. What I like about it is that it overloads exactly what needs to be overloaded---the representation of the type---without the need for any fake parameters. To make things concrete, here is some code: > newtype TypeRepT t = TR TypeRep > > class Typeable t where > typeRep :: TypeRepT t > > instacne Typeable Int where typeRep = TR type_rep_for_int > instance Typeable [] where typeRep = TR type_rep_for_list The two formulations support exactly the same interface (you can define `Proxy` and the proxied `typeRep` in terms of this class) so I wouldn't say that the one is easier to use that the other, but I think that this formulation is slightly simpler because it avoids the dummy parameter to typeRep. -Iavor

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Changes to Typeable
by Simon Peyton-Jones 14 Feb '12

14 Feb '12

Friends The page describes an improved implementation of the Typeable class, making use of polymorphic kinds. Technically it is straightforward, but it represents a non-backward-compatible change to a widely used library, so we need to make a plan for the transition. http://hackage.haskell.org/trac/ghc/wiki/GhcKinds/PolyTypeable Comments? You can fix typos or add issues directly in the wiki page, or discuss by email Simon

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read-Int implementation
by Serge D. Mechveliani 13 Feb '12

13 Feb '12

Who can tell, please, how read string :: Integer is implemented in ghc-7.4.1 ? Is it linked from the GMP (Gnu Multi-Precision) library? It is suspiciosely fast :-) In my test on 10^5 strings of length l = 5, 20 it shows the cost order in l less than 1, as if it was O(log(l)), or O(squareRoot(l). This is even despite that the very forming of the string list by concat and by take l0Exp (strs l) seems to have large overhead. The impression is that I am missing something. Regards, ------ Sergei mechvel(a)botik.ru ------------------------------------------------------------------------- main = putStr (shows resSum "\n") where m = 1 :: Int -- edit this multiplicity: 1, 4 ... digits = (if m == 1 then id else reverse) ['0' .. '9'] :: [Char] l0 = 5 :: Int -- first length l0Exp = (10 :: Int)^l0 l = l0 * m -- second length strs :: Int -> [String] -- all digit strings of length n strs n = if n == 0 then [""] else concat [map (d :) (strs (pred n)) | d <- digits] strings = strs l segm = if m == 1 then strings else take l0Exp strings -- length segm is always 10^l0 resSum = sum [read str :: Integer | str <- segm] -- testPairs = [(str, read str :: Int) | str <- strings] -- correctness testing ------------------------------------------------------------------------ > ghc -O2 --make Main > time ./Main

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Kind error in GHC-7.4.1, works in GHC-7.2.2
by Roel van Dijk 12 Feb '12

12 Feb '12

Hello, I have some code that compiled fine in GHC-7.2.2 but fails in GHC-7.4.1 with a kind error. {-# LANGUAGE MagicHash, NoImplicitPrelude, PackageImports #-} import "base" Data.Function ( ($) ) import "base" GHC.Exts ( Int(I#) ) import "base" Prelude ( Integral, fromIntegral, toInteger ) import "integer-gmp" GHC.Integer.Logarithms ( integerLogBase# ) intLog :: (Integral a) => a -> a intLog x = fromIntegral $ I# $ integerLogBase# 10 (toInteger x) This results in the following error: Couldn't match kind `#' against `*' In the second argument of `($)', namely `I# $ integerLogBase# 10 (toInteger x)' In the expression: fromIntegral $ I# $ integerLogBase# 10 (toInteger x) In an equation for `intLog': intLog x = fromIntegral $ I# $ integerLogBase# 10 (toInteger x) Simply eliminating some $'s using parenthesis solves the problem: intLog x = fromIntegral $ I# (integerLogBase# 10 (toInteger x)) Why do I get the above kind error? Could it be a bug in GHC?

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ANNOUNCE: GHC 7.2.1 Release Candidate 1
by Ian Lynagh 11 Feb '12

11 Feb '12

We are pleased to announce the first release candidate for GHC 7.2.1: http://www.haskell.org/ghc/dist/7.2.1-rc1/ This includes the source and testsuite tarballs, installers for OS X and Windows, and bindists for amd64/Linux, i386/Linux, amd64/FreeBSD and i386/FreeBSD. Please test as much as possible; bugs are much cheaper if we find them before the release! Thanks Ian, on behalf of the GHC team

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GHC bugs
by glasgow-haskell-bugs＠haskell.org 10 Feb '12

10 Feb '12

Hello, You are receiving this mail because you are the reporter, or on the CC list, for one or more GHC tickets that are automatically having their priority reduced due to our post-release ticket handling policy: http://hackage.haskell.org/trac/ghc/wiki/WorkingConventions/BugTracker#Remi… The list of tickets for which you are the reporter or on the CC list is given below. If any of these are causing problems for you, please let us know on glasgow-haskell-bugs(a)haskell.org and we'll look at raising the priority. Better still, if you are able to make any progress on any of the tickets yourself (whether that be actually fixing the bug, or just making it easier for someone else to - for example, by making a small, self-contained test-case), then that would be a great help. We at GHC HQ have limited resources, so if anything is waiting for us to make progress then it can be waiting a long time! #2986 :info printing instances often isn't wanted: http://hackage.haskell.org/trac/ghc/ticket/2986 -- The GHC Team http://www.haskell.org/ghc/

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auto-orphans?
by Christian Maeder 10 Feb '12

10 Feb '12

Hi, in http://www.haskell.org/ghc/docs/7.4.1/html/users_guide/options-sanity.html I've found no description for -fwarn-auto-orphans Cheers Christian

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GHCi-7.4.1: Importing a non existing module succeeds
by Bas van Dijk 10 Feb '12

10 Feb '12

Should I file a bug for this: GHCi 7.2.2: > import I.Do.Not.Exist <no location info>: Could not find module `I.Do.Not.Exist' Use -v to see a list of the files searched for. GHCi 7.4.1: > import I.Do.Not.Exist > (and for the record: I.Do.Not.Exist does not exist) Bas

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