July 2016 - ghc-tickets

[GHC] #8944: Warn instead of stopping on misplaced Haddock comments
by GHC 17 Aug '18

17 Aug '18

#8944: Warn instead of stopping on misplaced Haddock comments -------------------------------------+------------------------------------- Reporter: Fuuzetsu | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Parser) | Version: 7.9 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Given a simple module like {{{ module H where data F = F () -- ^ Comment for first type argument () }}} and trying to run Haddock on it, we'll get back {{{ /tmp/H.hs:4:12: parse error on input ‘(’ }}} The error message is rather sub-par in this scenario. It'd be great if we could instead print a warning saying that a Haddock comment is unexpected in that position and then continue on parsing. Best case scenario would be a more informative message such as “Documenting each constructor argument is not supported” but that might be quite a bit harder. Filing on GHC Trac as it's the parser that needs changing I believe. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8944> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9214: UNPACK support for sum types
by GHC 11 Aug '18

11 Aug '18

#9214: UNPACK support for sum types ------------------------------------+------------------------------------- Reporter: mojojojo | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Currently the pragma only supports single-constructor types. So in the following example it will simply be ignored: {{{ data A = A1 Char | A2 {-# UNPACK #-} !B data B = B1 Int | B2 Bool }}} However the problem seems to be easily solvable by denormalizing the type {{{A}}} to something like the following during unpacking: {{{ data A = A1 Char | A2_1 Int | -- from B1 A2_2 Bool -- from B2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9214> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12065: there is a way to override the .tix path with HPCTIXFILE
by GHC 11 Aug '18

11 Aug '18

#12065: there is a way to override the .tix path with HPCTIXFILE -------------------------------------+------------------------------------- Reporter: kostmo | Owner: Type: bug | Status: new Priority: normal | Milestone: 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: -------------------------------------+------------------------------------- Under the [https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/hpc.html#id… "Caveats and Shortcomings of Haskell Program Coverage" section], it says: > There is no way to change the name of the .tix file generated, apart from renaming the binary. However, specifying `HPCTIXFILE` as an environment variable when running the executable program does change the output path of the `.tix` file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12065> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9334: Implement "instance chains"
by GHC 09 Aug '18

09 Aug '18

#9334: Implement "instance chains" -------------------------------------+------------------------------------- Reporter: diatchki | Owner: diatchki Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.9 checker) | Differential Revisions: Keywords: | Architecture: Operating System: Unknown/Multiple | Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- It would be useful to implement a version of "instance chains" [1] in GHC, which would eliminate the need for OVERLAPPING_INSTANCES in most (all practcial?) programs. The idea is that programmers can explicitly group and order instances into an "instance chain". For example: {{{ instance (Monad m) => StateM (StateT s m) s where ... else (MonadTrans t, StateM m s) => StateM (t m) s where ... }}} When GHC searches for instances, the instances in a chain are considered together and in order, starting with the first one: 1. If the goal matches the current instance's head, then this instance is selected and the rest are ignored, as if they were not there; 2. If the goal does not match the current instance's head, AND it does not unify with the current instance's head, then we skip the instance and proceed to the next member of the chain; 3. If the goal does not match the current instance's head, but it does unify with it, then we cannot use this chain to solve the goal. In summary: earlier instances in a chain "hide" later instances, and later instances can be reached only if we are sure that none of the previous instance will match. [1] http://web.cecs.pdx.edu/~mpj/pubs/instancechains.pdf -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9334> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12002: Pragmas after a module declaration are ignored without warning.
by GHC 08 Aug '18

08 Aug '18

#12002: Pragmas after a module declaration are ignored without warning. -------------------------------------+------------------------------------- Reporter: seanparsons | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Normally pragmas are placed above the module declaration like so: {{{#!hs {-# LANGUAGE OverloadedStrings #-} module Main where }}} However if the above 2 lines are flipped around like this: {{{#!hs module Main where {-# LANGUAGE OverloadedStrings #-} }}} Then the behaviour seen by a user is that equivalent to the pragma not being present, because it would appear GHC ignores the multi-line comment it looks like. For a novice (I'm not one but it just tripped me up) this would be incredibly baffling (it was for me), it would be nice to see a warning for this at the least. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12002> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12043: internal error: evacuate: strange closure type
by GHC 08 Aug '18

08 Aug '18

#12043: internal error: evacuate: strange closure type -------------------------------------+------------------------------------- Reporter: mattchan | Owner: Type: bug | Status: new Priority: normal | Milestone: Research needed Component: Compiler | Version: 7.10.3 Keywords: internal | Operating System: Unknown/Multiple error, strange closuren | Architecture: ia64 | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Scary error while building Liquid Haskell from source: {{{ $ stack install [truncated] text-1.2.2.1: copy/register Progress: 40/61 -- While building package Cabal-1.22.8.0 using: /Users/matt/.stack/setup-exe-cache/x86_64-osx/setup-Simple- Cabal-1.22.5.0-ghc-7.10.3 --builddir=.stack- work/dist/x86_64-osx/Cabal-1.22.5.0 build --ghc-options " -ddump-hi -ddump-to-file" Process exited with code: ExitFailure (-6) Logs have been written to: /Users/matt/liquid/liquidhaskell/.stack- work/logs/Cabal-1.22.8.0.log Configuring Cabal-1.22.8.0... Building Cabal-1.22.8.0... Preprocessing library Cabal-1.22.8.0... [ 1 of 81] Compiling Paths_Cabal ( .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/autogen/Paths_Cabal.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Paths_Cabal.o ) [ 2 of 81] Compiling Distribution.TestSuite ( Distribution/TestSuite.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/TestSuite.o ) [ 3 of 81] Compiling Distribution.Simple.PreProcess.Unlit ( Distribution/Simple/PreProcess/Unlit.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Simple/PreProcess/Unlit.o ) [ 4 of 81] Compiling Distribution.GetOpt ( Distribution/GetOpt.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/GetOpt.o ) [ 5 of 81] Compiling Distribution.PackageDescription.Utils ( Distribution/PackageDescription/Utils.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/PackageDescription/Utils.o ) [ 6 of 81] Compiling Distribution.Simple.CCompiler ( Distribution/Simple/CCompiler.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Simple/CCompiler.o ) [ 7 of 81] Compiling Distribution.Compat.Binary ( Distribution/Compat/Binary.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Compat/Binary.o ) [ 8 of 81] Compiling Distribution.Compat.ReadP ( Distribution/Compat/ReadP.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Compat/ReadP.o ) [ 9 of 81] Compiling Distribution.Text ( Distribution/Text.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Text.o ) [10 of 81] Compiling Distribution.Version ( Distribution/Version.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Version.o ) [11 of 81] Compiling Language.Haskell.Extension ( Language/Haskell/Extension.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Language/Haskell/Extension.o ) [12 of 81] Compiling Distribution.Compiler ( Distribution/Compiler.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Compiler.o ) [13 of 81] Compiling Distribution.Simple.Compiler ( Distribution/Simple/Compiler.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Simple/Compiler.o ) [14 of 81] Compiling Distribution.Simple.GHC.ImplInfo ( Distribution/Simple/GHC/ImplInfo.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Simple/GHC/ImplInfo.o ) [15 of 81] Compiling Distribution.License ( Distribution/License.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/License.o ) [16 of 81] Compiling Distribution.ModuleName ( Distribution/ModuleName.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/ModuleName.o ) [17 of 81] Compiling Distribution.Package ( Distribution/Package.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/Package.o ) [18 of 81] Compiling Distribution.System ( Distribution/System.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/System.o ) [19 of 81] Compiling Distribution.PackageDescription ( Distribution/PackageDescription.hs, .stack- work/dist/x86_64-osx/Cabal-1.22.5.0/build/Distribution/PackageDescription.o ) ghc: internal error: evacuate: strange closure type 41832616 (GHC version 7.10.3 for x86_64_apple_darwin) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} [[Image(http://i.imgur.com/T44UPg0.png)]] -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12043> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10927: IndexError: pop from empty list
by GHC 08 Aug '18

08 Aug '18

#10927: IndexError: pop from empty list -------------------------------------+------------------------------------- Reporter: schwab | Owner: hvr Type: bug | Status: new Priority: normal | Milestone: Component: Trac & Git | Version: Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | -------------------------------------+------------------------------------- ==== Zum Reproduzieren ==== Während der Ausführung von GET auf `/attachment/ticket/10926/` hat Trac einen internen Fehler gemeldet. ''(Bitte geben Sie hier weitere Details an)'' Anfrageparameter: {{{ {u'action': u'new', 'path': u'10926/', 'realm': u'ticket'} }}} User agent: `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.21 (KHTML, like Gecko) konqueror/4.14.9 Safari/537.21` ==== Systeminformationen ==== ''Systeminformation nicht verfügbar'' ==== Aktive Plugins ==== ''Plugininformation nicht verfügbar'' ==== Python-Zurückverfolgungsinformationen ==== {{{ Traceback (most recent call last): File "/usr/local/lib/python2.7/dist- packages/Trac-1.0.9-py2.7.egg/trac/web/main.py", line 554, in _dispatch_request dispatcher.dispatch(req) File "/usr/local/lib/python2.7/dist- packages/Trac-1.0.9-py2.7.egg/trac/web/main.py", line 267, in dispatch iterable=chrome.use_chunked_encoding) File "/usr/local/lib/python2.7/dist- packages/Trac-1.0.9-py2.7.egg/trac/web/chrome.py", line 1111, in render_template encoding='utf-8') File "/usr/local/lib/python2.7/dist-packages/genshi/core.py", line 184, in render return encode(generator, method=method, encoding=encoding, out=out) File "/usr/local/lib/python2.7/dist-packages/genshi/output.py", line 58, in encode for chunk in iterator: File "/usr/local/lib/python2.7/dist-packages/genshi/output.py", line 350, in __call__ for kind, data, pos in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/output.py", line 829, in __call__ for kind, data, pos in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/output.py", line 669, in __call__ for kind, data, pos in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/output.py", line 774, in __call__ for kind, data, pos in chain(stream, [(None, None, None)]): File "/usr/local/lib/python2.7/dist-packages/genshi/output.py", line 594, in __call__ for ev in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/core.py", line 289, in _ensure for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/core.py", line 289, in _ensure for event in stream: File "/usr/local/lib/python2.7/dist- packages/Trac-1.0.9-py2.7.egg/trac/web/chrome.py", line 1309, in _strip_accesskeys for kind, data, pos in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/core.py", line 289, in _ensure for event in stream: File "/usr/local/lib/python2.7/dist- packages/Trac-1.0.9-py2.7.egg/trac/web/chrome.py", line 1298, in _generate for kind, data, pos in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/core.py", line 289, in _ensure for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/core.py", line 289, in _ensure for event in stream: File "/usr/local/lib/python2.7/dist- packages/genshi/filters/transform.py", line 706, in _unmark for mark, event in stream: File "/usr/local/lib/python2.7/dist- packages/genshi/filters/transform.py", line 1101, in __call__ for mark, event in stream: File "/usr/local/lib/python2.7/dist- packages/genshi/filters/transform.py", line 118, in __iter__ event = self.stream.next() File "/usr/local/lib/python2.7/dist- packages/genshi/filters/transform.py", line 734, in __call__ for mark, event in stream: File "/usr/local/lib/python2.7/dist- packages/genshi/filters/transform.py", line 702, in _mark for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/template/base.py", line 618, in _include for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/template/markup.py", line 378, in _match ctxt, start=idx + 1, **vars): File "/usr/local/lib/python2.7/dist-packages/genshi/template/markup.py", line 378, in _match ctxt, start=idx + 1, **vars): File "/usr/local/lib/python2.7/dist-packages/genshi/template/markup.py", line 362, in _match content = list(content) File "/usr/local/lib/python2.7/dist-packages/genshi/template/base.py", line 618, in _include for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/template/markup.py", line 326, in _match for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/template/markup.py", line 315, in _strip event = next() File "/usr/local/lib/python2.7/dist-packages/genshi/template/base.py", line 558, in _flatten for kind, data, pos in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/core.py", line 289, in _ensure for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/path.py", line 588, in _generate subevent = next() File "/usr/local/lib/python2.7/dist-packages/genshi/template/base.py", line 618, in _include for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/template/markup.py", line 315, in _strip event = next() File "/usr/local/lib/python2.7/dist-packages/genshi/template/base.py", line 558, in _flatten for kind, data, pos in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/core.py", line 289, in _ensure for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/path.py", line 588, in _generate subevent = next() File "/usr/local/lib/python2.7/dist-packages/genshi/template/base.py", line 618, in _include for event in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/template/markup.py", line 315, in _strip event = next() File "/usr/local/lib/python2.7/dist-packages/genshi/template/base.py", line 558, in _flatten for kind, data, pos in stream: File "/usr/local/lib/python2.7/dist-packages/genshi/filters/i18n.py", line 178, in _generate for event in msgbuf.translate(gettext(msgbuf.format())): File "/usr/local/lib/python2.7/dist-packages/genshi/filters/i18n.py", line 1051, in translate events = self.events[order].pop(0) IndexError: pop from empty list }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10927> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12421: TestEquality and TestCoercion documentation is confusing
by GHC 08 Aug '18

08 Aug '18

#12421: TestEquality and TestCoercion documentation is confusing -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Core | Version: 8.0.1 Libraries | 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: -------------------------------------+------------------------------------- Currently, the documentation for the `TestEquality` class indicates > This class contains types where you can learn the equality of two types from information contained in terms. Typically, only singleton types should inhabit this class. The `TestCoercion` documentation includes a similar caution about singleton types. But this is far too conservative! Length-indexed vectors can be made valid instances of `TestEquality` and `TestCoercion` in exactly one way: {{{#!hs data Nat = Z | S Nat data Vec a n where Nil :: Vec a 'Z Cons :: a -> Vec a n -> Vec a ('S n) instance TestEquality (Vec a) where testEquality Nil Nil = Just Refl testEquality (Cons _ xs) (Cons _ ys) = fmap (\Refl -> Refl) (testEquality xs ys) testEquality _ _ = Nothing instance TestCoercion (Vec a) where testCoercion xs ys = fmap (\Refl -> Coercion) (testEquality xs ys) }}} Polykinded heterogeneous lists are another nice non-singleton example for which each class has a single "most reasonable" instance: {{{#!hs data HList (f :: k -> *) (xs :: [k]) where HNil :: HList f '[] HCons :: f a -> HList f as -> HList f (a ': as) instance TestEquality f => TestEquality (HList f) where testEquality HNil HNil = Just Refl testEquality (HCons x xs) (HCons y ys) = do Refl <- testEquality x y Refl <- testEquality xs ys Just Refl testEquality _ _ = Nothing instance TestCoercion f => TestCoercion (HList f) where testCoercion HNil HNil = Just Coercion testCoercion (HCons x xs) (HCons y ys) = do Coercion <- testCoercion x y Coercion <- testCoercion xs ys Just Coercion testCoercion _ _ = Nothing }}} I don't know just how far the warning should be weakened; it may make sense to go as far as saying the type should generally be a GADT. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12421> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10599: Template Haskell doesn't allow `newName "type"`
by GHC 07 Aug '18

07 Aug '18

#10599: Template Haskell doesn't allow `newName "type"` -------------------------------------+------------------------------------- Reporter: meteficha | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 7.10.1 Haskell | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Using `type` as a name is, of course, forbidden. OTOH, `type_1` is allowed as a name. However, using GHC 7.10.1 and `ghc --make T.hs` on files: {{{#!hs -- T.hs {-# LANGUAGE TemplateHaskell #-} module T where import Q test -- Q.hs module Q where import Language.Haskell.TH test :: Q [Dec] test = do t <- newName "type" return [FunD t [Clause [] (NormalB $ LitE $ CharL 't') []]] }}} Leads to the following error: {{{ $ ghc --make -ddump-splices T.hs [2 of 2] Compiling T ( T.hs, T.o ) T.hs:6:1: Illegal variable name: ‘type’ When splicing a TH declaration: ident_0 type_1 = type_1 }}} The above example works fine for GHC 7.8.4, so it's a regression. Reference: https://github.com/yesodweb/persistent/issues/412 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10599> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10355: Dynamic linker not initialised
by GHC 07 Aug '18

07 Aug '18

#10355: Dynamic linker not initialised -------------------------------------+------------------------------------- Reporter: dpiponi | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- I get this message: [ 3 of 24] Compiling Cable ( src/Cable.hs, dist/build/ui/ui- tmp/Cable.o ) <no location info>: ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-apple-darwin): Dynamic linker not initialised Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug when building my code here: https://github.com/dpiponi/Moodler/tree/master/Moodler/src under Yosemite 10.10.2 So I'm reporting it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10355> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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