August 2016 - ghc-tickets

[GHC] #12418: Make `MonadCont (ContT r m)` polykinded (r::k), (m::k -> Type)
by GHC 11 Aug '16

11 Aug '16

#12418: Make `MonadCont (ContT r m)` polykinded (r::k), (m::k -> Type) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Core | Version: 8.0.1 Libraries | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- == Issue == The current `MonadCont (ContT r m)` instance seems to have `r::Type` and `m::Type -> Type`. While this is accepted {{{ >>> :t callCC :: ((a -> ContT r m b) -> ContT r m a) -> ContT r m a callCC :: ((a -> ContT r m b) -> ContT r m a) -> ContT r m a :: ((a -> ContT r m b) -> ContT r m a) -> ContT r m a }}} this gets rejected {{{ >>> :set -XPolyKinds >>> :t callCC :: ((a -> ContT r m b) -> ContT r m a) -> ContT r m a <interactive>:1:1: error: • No instance for (MonadCont (ContT r1 m1)) arising from a use of ‘callCC’ • In the expression: callCC :: ((a -> ContT r m b) -> ContT r m a) -> ContT r m a }}} and this doesn't reduce {{{ >>> :t callCC @(ContT _ _) callCC @(ContT _ _) :: MonadCont (ContT t t1) => ((a -> ContT t t1 b) -> ContT t t1 a) -> ContT t t1 a }}} the kinds must be specified {{{ >>> :t callCC @(ContT (_::Type) _) callCC @(ContT (_::Type) _) :: ((a -> ContT t t1 b) -> ContT t t1 a) -> ContT t t1 a }}} == Solution == This is unfortunate since since `callCC` can be kind polymorphic: {{{#!hs newtype ContT' r m a = ContT' { runContT' :: (a -> m r) -> m r } callCC' :: forall k a (r :: k) (m :: k -> Type) b. ((a -> ContT' r m b) -> ContT' r m a) -> ContT' r m a callCC' f = ContT' $ \ c -> runContT' (f (\ x -> ContT' $ \ _ -> c x)) c instance forall k (r::k) (m::k -> Type). MonadCont (ContT' r m) where callCC = callCC' }}} this works now {{{ >>> :t callCC @(ContT' _ _) callCC @(ContT' _ _) :: forall k (t :: k) (t1 :: k -> *) a b. ((a -> ContT' t t1 b) -> ContT' t t1 a) -> ContT' t t1 a }}} {{{ >>> :t callCC :: ((a -> ContT' r m b) -> ContT' r m a) -> ContT' r m a callCC :: ((a -> ContT' r m b) -> ContT' r m a) -> ContT' r m a :: forall k a (r :: k) (m :: k -> *) b. ((a -> ContT' r m b) -> ContT' r m a) -> ContT' r m a }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12418> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12481: Add MonadFail instance for Either String
by GHC 11 Aug '16

11 Aug '16

#12481: Add MonadFail instance for Either String -------------------------------------+------------------------------------- Reporter: hesiod | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Core | Version: Libraries | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- There seems to be the low hanging fruit of a MonadFail instance for Either String. {{{#!hs instance MonadFail (Either String) where fail = Left }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12481> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12480: Clever mit Revolyn zur Traumfigur
by GHC 11 Aug '16

11 Aug '16

#12480: Clever mit Revolyn zur Traumfigur -------------------------------------+------------------------------------- Reporter: | Owner: anastasija.hansen92 | Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Kombination der beiden Produkte: „Revolyn Tabletten “ und „Pure Cleannse Tabletten“ ergeben kombiniert die perfekte Basis für eine erfolgreiche Diät. Während „Revolyn“ die Fettverbrennung immens beschleunigt, erfüllt die „[http://www.healthprodukte.reviews; Pure Cleanse] Pille“ andere wichtige Punkte. Es steigert extrem ihre Energie, reinigt und entgiftet ihren Organismus und bringt jedermanns Stoffwechsel in Schwung! Es verhindert also die gebräuchlichen Nebenwirkungen einer Diät: das Trägheitsgefühl, die 0-Bock-Phase und die Bauchschmerzen. Inhaltsstoffe von Revolyn: Doch wie ist das alles möglich? Guckt man sich den Inhalt mal im Einzelnen an. Die Revolyn Tablette beinhaltet gleich mehrere natürliche und effektive Inhaltsstoffe. Der grüne Tee und die beinhaltenden Guarana- Bestandteile steigern gehörig den Stoffwechsel. Ferner erhöht Guarana den Puls und aus dem Grund auch den Kalorienverbrauch.Der Bestandteil„Damiana“ ermöglicht eine verbesserte Libido, steigert die Fettverbrennung und stärkt das Nerven- und Immunsystem! Ein echtes Allround-Talent!Das außerdem enthaltene Granatapfel-Extrakt wirkt positiv auf die Blutfette (verbessert dessen Vernichtung) und beinhaltet unglaublich viele gute und für den Körper wichtige Vitamine. Einnahme von den Revolyn-Diäthelfern: Die Verabreichung von Revolyn Tabletten ist super einfach erklärt. Morgens und Am Abend eine Tablette mit einem Glas mit zuckerfreiem Getränk zu sich nehmen – fertig. Das Einnehmen von „Pure Life Cleanse ist noch einfacher und konsumentenfreundlicher: Eine Tablette am Nachmittag mit einem Schluck Wasser runterschlucken, et ce ca! Wie teuer sind die Revolyn-Diäthelfer? Gegenüber anderen Abnehmprodukten mit einer ähnlichen Wirkung „ist [http://www.healthprodukte.reviews/revolyn-pure-cleanse/; Revolyn] “ und „die Pure Cleanse Diät Tabletten“ ist Revolyn recht günstig. Zwar kostet 1 Flasche 39,95 €, allerdings verringert sich der Stück-Preis je nach Bestellmenge. Wenn jemand 2 Flaschen bestellt (79,95Euro) erhält eine für lau dazu. 4 Flaschen kosten 159,80 Taler, erhält aber auch 4 Flaschen für lau obendrauf. Effektiv bekommt ihr also acht Flaschen für nur 159,80 Euro! Ein einzigartiger Hammer! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12480> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11646: Make pattern synonym export type mismatch a warning
by GHC 11 Aug '16

11 Aug '16

#11646: Make pattern synonym export type mismatch a warning -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc2 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- As I understand it, attempting to associate a pattern synonym with a type constructor that it "obviously" doesn't match is an error. This is strange for two reasons: 1. An "erroneous" association cannot compromise type safety. 2. The test is incomplete. Therefore, I believe such mismatches should lead to warnings instead of errors. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11646> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10106: GHC doesn't warn on typos in language pragmas
by GHC 11 Aug '16

11 Aug '16

#10106: GHC doesn't warn on typos in language pragmas -------------------------------------+------------------------------------- Reporter: sdemos | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Linux Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- In particular, I was struggling with the QuasiQuotes language extension. I had - {{{#!hs {-# LANGAUGE QuasiQuotes #-} site = [shamelet|Hello World!|] }}} Notice the transposed A and U in `LANGUAGE` The error that ghc was emitting was - `Main.hs:23:47: parse error on input ‘]’` It took me a long time and a lot of head-banging to figure out that it was a typo in the language pragma, especially because the language pragma was surrounded by other language pragmas and it was at the top of the file. I would think that this should at least emit a warning when there is a typo in a pragma. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10106> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2867: Make a way to tell GHC that a pragma name should be "recognised"
by GHC 11 Aug '16

11 Aug '16

#2867: Make a way to tell GHC that a pragma name should be "recognised" -------------------------------------+------------------------------------- Reporter: igloo | Owner: Type: feature request | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 6.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by Lemming): * cc: ghc@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2867#comment:19> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12377: getExecutablePath doesn't return absolute path on OpenBSD (and maybe other OS also)
by GHC 11 Aug '16

11 Aug '16

#12377: getExecutablePath doesn't return absolute path on OpenBSD (and maybe other OS also) -------------------------------------+------------------------------------- Reporter: oherrala | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 8.0.1 libraries/base | Keywords: | Operating System: OpenBSD Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- System.Environment.getExecutablePath doesn't return absolute path to executable in OpenBSD. This happens because getExecutablePath uses argv[0] to determine path and argv[0] might not be absolute path. My environment: {{{ $ uname -a OpenBSD fizbuz.pilkki.ciz.fi 6.0 GENERIC.MP#2274 amd64 $ ghc -V The Glorious Glasgow Haskell Compilation System, version 7.10.3 }}} This test program in OpenBSD: {{{#!hs module Main where import System.Environment main = getExecutablePath >>= print }}} returns {{{ $ ./test "./test" }}} For example in OS X the call returns absolute path: {{{ $ ./test "/Users/oherrala/tmp/test" }}} OpenBSD is one of the operating systems which gets fall back to using argv[0] to determine exec's location: https://git.haskell.org/ghc.git/blob/HEAD:/libraries/base/System/Environmen… Maybe the argv[0] result should be wrapped with realpath(3) to get absolute path? This bug is also present in cabal-install and reported here: https://github.com/haskell/cabal/issues/3512#issuecomment-231604356 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12377> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12172: User's Guide patches
by GHC 07 Aug '16

07 Aug '16

#12172: User's Guide patches -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: task | Status: new Priority: normal | Milestone: 8.0.2 Component: Documentation | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Documentation Unknown/Multiple | bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- If you want your User's Guide patches to be merged to the 8.0 branch, please mention this ticket in the commit message. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12172> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12007: Pattern families regression
by GHC 07 Aug '16

07 Aug '16

#12007: Pattern families regression -------------------------------------+------------------------------------- Reporter: MikeIzbicki | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following code compiles fine for me in GHC 7.10.1, but fails in GHC 8.1.20160502 {{{ {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE ViewPatterns #-} data Foo a = Foo a a pattern A a1 a2 = Foo a1 a2 pattern B a1 a2 = A a1 a2 }}} The problem is the nested pattern. Compiling gives: {{{ [1 of 1] Compiling Main ( Bug1.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20160502 for x86_64-unknown-linux): kindPrimRep.go rep_a85f Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12007> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7105: Better names for derived SCCs of instances
by GHC 07 Aug '16

07 Aug '16

#7105: Better names for derived SCCs of instances -------------------------------------+------------------------------------- Reporter: ksf | Owner: simonmar Type: feature request | Status: closed Priority: normal | Milestone: 8.0.2 Component: Profiling | Version: 7.4.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #11543 | Differential Rev(s): Phab:D2282 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: merge => closed * resolution: => fixed * milestone: => 8.0.2 Comment: Merged as 7fc7538fffb9ad4ad2132a8a9ef8cb6543d0b2fc. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7105#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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