- ghc-devs - Haskell.org

TH changes for ghc 8.0
by Erik de Castro Lopo 12 Apr '16

12 Apr '16

Hi all, I'm working on updating persistent-template for ghc-8.0 and reading the migration guide: https://ghc.haskell.org/trac/ghc/wiki/Migration/8.0#template-haskell-2.11.0… specifically the bit that says: > * the DataD, NewtypeD, DataInstD, and NewtypeInstD constructors have a new > field `Maybe Kind` (#10828), and take a `CxtQ` instead of a `[Name]` for > the derived classes (#10819). If you don't know what to do, use `Nothing` > for the kind signature, and `cxt []` for the derived classes. Using `Nothing` as suggested is working out well enough, but I'm a bit befuddled by the change from `[Name]` to `CtxQ` and the usage of `ctx []`. I can't seem to find *any* function named `ctx`. Any light people may be about to shed on this would be much appreciated. Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/

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Broken haddock in new GHC HEAD build
by Conal Elliott 12 Apr '16

12 Apr '16

I built GHC HEAD from git yesterday (using GHC 7.10.3 on Mac OS 10.9.5), and the haddock I got dies with bash-3.2$ haddock --version dyld: Symbol not found: _ghc_GHC_modInfoExportszugo_info Referenced from: /Users/conal/git-repos/ghc-2016-04-05/inplace/lib/bin/haddock Expected in: /Users/conal/git-repos/ghc-2016-04-05/compiler/stage2/build/libHSghc-8.1-ghc8.1.20160405.dylib in /Users/conal/git-repos/ghc-2016-04-05/inplace/lib/bin/haddock Trace/BPT trap: 5 Luckily, I have a working haddock from 2016-03-07 sources that I copied into my new GHC bin (~/git-repos/ghc-2016-04-05/inplace/bin/) for now. -- Conal

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how to cabal-install with ghc-8.rc3 ?
by Johannes Waldmann 11 Apr '16

11 Apr '16

Hi. I would love to test rc3. Building (with 7.10.3) from source went fine. But then I cannot cabal-install anything: random-1.1: installed package info from too old version of Cabal (key field does not match id field) Failed to install random-1.1 What is the recommended upgrade path? ( bootstrap.sh in cabal/cabal-install (current from github) does not work, tries to download a Cabal version that's not on hackage ) Thanks, J.W.

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GHC 8.0.1-rc3 and required version of elfutils [Was: GHC 8.0.1-rc3 source tarball availability]
by Andrés Sicard-Ramírez 11 Apr '16

11 Apr '16

On 10 April 2016 at 20:55, Ben Gamari <ben(a)well-typed.com> wrote: > I've pushed a new tarball based on > 9c48d8a02dd80bba3bd313bc52add841530e28dc. I have pushed essentially > everything into this candidate that I expect will go into 8.0.1. It > validates but it isn't nearly as well tested as the previous tree. I'll > try doing some further builds tomorrow and let you all know if anything > goes awry. >From running `./configure` on http://downloads.haskell.org/~ghc/8.0.1-rc3/ghc-8.0.0.20160408-x86_64-unkno… it seems that the required version of elfutils is 0.158, however this version of elfutils is not checked when running `./configure` on http://downloads.haskell.org/~ghc/8.0.1-rc3/ghc-8.0.0.20160411-src.tar.xz That is, instead of get an error on configuration time because my version of elfutils is too old, I get an error on compilation time. -- Andrés

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heres an integer-simple build of ghc 7.10.3 for OS X
by Carter Schonwald 10 Apr '16

10 Apr '16

1-2 industrial folks who need to distribute applications on mac seem to have trouble building ghc 7.10.3 with integer simple on OS X 10.11 (probably because of various build tool changes that happened), so I took the time to make a build on my 10.10 mac. should be useful for others too! http://www.wellposed.com.s3.amazonaws.com/opensource/ghc/releasebuild-unoff… https will work,but you'll get a warning that its an aws wildcard cert :) for those who prefer https and dont mind the cert warning https://www.wellposed.com.s3.amazonaws.com/opensource/ghc/releasebuild-unof… shasum -a512 ghc-7.10.3-x86_64-apple-darwin-integer-simple-built-by-carter.tar.bz2 is 37ccb3c3fe3f21b7c56ed09b8c3d59601bde21d651d17609f62b4b41f3658e6f5a7089a0b271d44d18ba856256681a124bc34b3525c245f4917940a66a3aec63

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Odd error message due to PolyKinds
by Kosyrev Serge 10 Apr '16

10 Apr '16

Good day folks, Here is a test case that exposes a certain weakness in PolyKinds error messaging. In the following snippet (T W) :: * is malkinded: > {-# LANGUAGE PolyKinds #-} > {-# LANGUAGE UnicodeSyntax #-} > > class Eq a ⇒ EqSyn a where > data T w > data W f > > x = (undefined ∷ EqSyn w ⇒ T w → ()) (undefined ∷ T W) 8.0.1rc2 yields: > ../ghc-playground.hs:8:42: error: > • Expected kind ‘T W’, but ‘undefined :: T W’ has kind ‘T W’ > • In the first argument of ‘undefined :: > EqSyn w => T w -> ()’, namely > ‘(undefined :: T W)’ > In the expression: > (undefined :: EqSyn w => T w -> ()) (undefined :: T W) > In an equation for ‘main’: > main = (undefined :: EqSyn w => T w -> ()) (undefined :: T W) ..which is.. not informative. With PolyKinds removed: > ../ghc-playground.hs:7:56: error: > • Expecting one more argument to ‘W’ > Expected a type, but ‘W’ has kind ‘* -> *’ > • In the first argument of ‘T’, namely ‘W’ > In an expression type signature: T W > In the first argument of ‘undefined :: > EqSyn w => T w -> ()’, namely > ‘(undefined :: T W)’ I'm not sure if this was reported, so I'm sorry for the noise if it was. -- с уважениeм / respectfully, Косырев Сергей

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Benchmarking harnesses for a more modern nofib?
by Ryan Newton 07 Apr '16

07 Apr '16

Hi all, Is anyone currently working in, or interested in helping with, a new benchmark suite for Haskell? Perhaps, packaging up existing apps and app benchmarks into a new benchmark suite that gives a broad picture of Haskell application performance today? Background: We run nofib, and we run the shootout benchmarks. But when we want to evaluate basic changes to GHC optimizations or data representation, these really don't give us a full picture of whether a change is beneficial. A few years ago, fibon <https://hackage.haskell.org/package/fibon> tried to gather some Hackage benchmarks. This may work even better with Stackage, where there are 180 benchmark suites among the 1770 packages currently. Also, these days companies are building substantial apps in Hackage. Which substantial apps could or should go into a benchmark suite? I see Warp and other web server benchmarks <http://www.infoq.com/news/2015/04/web-frameworks-benchmark-2015?utm_source=…> all over the web. But is there a harness that can time some of this code while running inside a single-machine, easy-setup benchmark suite? Best, -Ryan

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Trouble with first GHC patch submission: uncommitted changes
by Conal Elliott 07 Apr '16

07 Apr '16

I'm trying to get through my first GHC patch submission, using git and Phabricator, following directions at https://ghc.haskell.org/trac/ghc/wiki/Phabricator. "git status" shows two unstaged changes: "deleted: test spaces" and "modified: ../libraries/bytestring (modified content)" (in a submodule). I don't know where either change came from. When I use "arc diff" to submit my intended change to the compiler, I get asked about these to uncommitted changes. I say to ignore the submodule change and do not amend my commit with the "test spaces" deletion, I get "Usage Exception: You can not continue with uncommitted changes. Commit or discard them before proceeding." I don't know how to discard (nor whether safe), and I don't think I want to commit. Note: the directions say to use "arc diff~" (rather than "arc diff"), to which arc replied "(Assuming 'diff~' is the British spelling of 'diff'.)". Thanks for any help! -- Conal

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"opt_univ fell into a hole"
by Conal Elliott 06 Apr '16

06 Apr '16

I'm getting the following error message from a GHC plugin I'm developing (note GHC version): ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20160307 for x86_64-apple-darwin): opt_univ fell into a hole {aD1S} I don't get this error when compiling without my plugin, so I may well be violating a compiler invariant. Shortly before the error, the plugin produced the following dictionary expression, which does indeed contain a `UnivCo` with a `HoleProv`. The plugin does sometimes generate `UnivCo`s but not with `HoleProv`. let { $dHasRep_aD1T :: HasRep (Vec 'Z s_aD1R[fuv:0]) $dHasRep_aD1T = $fHasRepVec0 @ s_aD1R[fuv:0] } in let { $dHasRepZLVeczqZZZLKeyhZRZR_Ii5CR :: HasRep (Vec 'Z (Key h_aCnh)) $dHasRepZLVeczqZZZLKeyhZRZR_Ii5CR = $dHasRep_aD1T `cast` ((HasRep (Vec <'Z>_N (Sym U(hole:{aD1S}, Key h_aCnh, s_aD1R[fuv:0])_N))_N)_R :: HasRep (Vec 'Z s_aD1R[fuv:0]) ~R# HasRep (Vec 'Z (Key h_aCnh))) } in $dHasRepZLVeczqZZZLKeyhZRZR_Ii5CR Here, `Key` is a type family from `Data.Key` in the keys package, and `Vec` is a GADT of statically length-indexed lists. Suggestions? Thanks, - Conal

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Feature development
by Sazanovich Nikita 06 Apr '16

06 Apr '16

Hello! I am working on ticket https://ghc.haskell.org/trac/ghc/ticket/5850 <https://ghc.haskell.org/trac/ghc/ticket/5850> now. I’ve come upon converting the type, which GHC.compileExpr returns, to my prompt function type [PModule] -> Int -> IO String. But this function returns ghc-prim-0.5.0.0:GHC.Prim.Any. I don’t see a clear way to convert it. So my questions are: - What this type is about? I know Any type in Haskell. Is it a specific version of it? - Or maybe it is not the best way to check a function correctness? I’ve checked out InteractiveEval module and it seems that there are only four quite similar functions to compile Expressions. Last person, who was trying to solve this problem, used Unsafe.Coerce and it is also doing this job pretty well now, but the name speaks for itself. Thank you.

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