November 2018 - ghc-tickets

[GHC] #10949: Document typed Template Haskell
by GHC 11 Jan '19

11 Jan '19

#10949: Document typed Template Haskell -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: high | Milestone: 8.0.1 Component: Template | Version: 7.10.2 Haskell | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Documentation Unknown/Multiple | bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | -------------------------------------+------------------------------------- As far as I can tell, typed Template Haskell is completely missing from the manual. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10949> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14838: missing "incomplete-patterns" warning for TH-generated functions
by GHC 11 Jan '19

11 Jan '19

#14838: missing "incomplete-patterns" warning for TH-generated functions -------------------------------------+------------------------------------- Reporter: gelisam | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 8.2.2 Haskell | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | error/warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- "incomplete-patterns" warnings are generated for TH-generated case expressions, but not for TH-generated functions, so the behaviour is inconsistent. For example: {{{#!hs {-# LANGUAGE TemplateHaskell #-} module Lib where import Language.Haskell.TH qIncompleteCase :: Q [Dec] qIncompleteCase = [d| incompleteCase :: Bool -> () incompleteCase b = case b of True -> () |] qIncompleteFunction :: Q [Dec] qIncompleteFunction =[d| incompleteFunction :: Bool -> () incompleteFunction True = () |] }}} {{{#!hs {-# LANGUAGE TemplateHaskell #-} module Bug where import Lib $qIncompleteCase $qIncompleteFunction incompleteCase' :: Bool -> () incompleteCase' b = case b of True -> () incompleteFunction' :: Bool -> () incompleteFunction' True = () }}} When compiling the above two files with `-Wall`, GHC 8.2.2 produces an "incomplete-patterns" warning for `qIncompleteCase`, `incompleteCase'`, and `incompleteFunction'`, but not for `qIncompleteFunction`. I would prefer to get a warning for `qIncompleteFunction` as well. My use case is the [https://hackage.haskell.org/package/surjective surjective] package, in which I intentionally generate code which produces warnings in order to warn the user about corresponding issues in their code. I could generate [https://github.com/gelisam/surjective/blob/master/src/Surjective.hs#L158-L1… better error messages] if GHC generated warnings for TH-generated functions as well. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14838> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15399: Build failure on PowerPC 64-bit big endian
by GHC 11 Jan '19

11 Jan '19

#15399: Build failure on PowerPC 64-bit big endian ---------------------------------+---------------------------------------- Reporter: trommler | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 Keywords: | Operating System: Linux Architecture: powerpc64 | Type of failure: Building GHC failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ---------------------------------+---------------------------------------- Building GHC 8.6.1 alpha 2 fails with these errors on Powerpc 64-bit big endian Linux: {{{ [ 5076s] utils/check-ppr/Main.hs:44:18: error: [ 5076s] * GHC internal error: `astFile' is not in scope during type checking, but it passed the renamer [ 5076s] tcl_env of environment: [agVj :-> Identifier[libdir::FilePath, NotLetBound], [ 5076s] agVk :-> Identifier[fileName::String, NotLetBound], [ 5076s] agVl :-> Identifier[p::a, NotLetBound], [ 5076s] agVo :-> Identifier[anns::ApiAnns, TopLevelLet [agVl :-> p] False], [ 5076s] agVp :-> Identifier[pragmas::String, TopLevelLet [agVo :-> anns] False], [ 5076s] agVq :-> Identifier[newFile::FilePath, TopLevelLet [agVk :-> fileName] False], [ 5076s] rfRp :-> Identifier[usage::String, TopLevelLet [] True], [ 5076s] rfU1 :-> Identifier[main::IO (), TopLevelLet [] True], [ 5076s] rfU2 :-> Identifier[testOneFile::FilePath [ 5076s] -> String [ 5076s] -> IO (), TopLevelLet [] True], [ 5076s] rfU3 :-> Identifier[parseOneFile::FilePath [ 5076s] -> FilePath [ 5076s] -> IO [ 5076s] ParsedModule, TopLevelLet [] True], [ 5076s] rfU4 :-> Identifier[getPragmas::ApiAnns -> String, TopLevelLet], [ 5076s] rfU5 :-> Identifier[pp::forall a. [ 5076s] Outputable a => [ 5076s] a -> String, TopLevelLet [] True]] [ 5076s] * In the first argument of `writeFile', namely `astFile' [ 5076s] In a stmt of a 'do' block: writeFile astFile origAst [ 5076s] In the expression: [ 5076s] do p <- parseOneFile libdir fileName [ 5076s] let pped = pragmas ++ "\n" ++ pp (pm_parsed_source p) [ 5076s] anns = pm_annotations p [ 5076s] .... [ 5076s] writeFile astFile origAst [ 5076s] writeFile newFile pped [ 5076s] .... [ 5076s] | [ 5076s] 44 | writeFile astFile origAst [ 5076s] | ^^^^^^^ [ 5076s] utils/check-ppr/ghc.mk:18: recipe for target 'utils/check-ppr /dist-install/build/Main.o' failed [ 5076s] make[1]: *** [utils/check-ppr/dist-install/build/Main.o] Error 1 [ 5076s] make[1]: *** Waiting for unfinished jobs.... [ 5077s] [ 5077s] utils/check-api-annotations/Main.hs:116:32: error: [ 5077s] * GHC internal error: `GenericQ' is not in scope during type checking, but it passed the renamer [ 5077s] tcl_env of environment: [agZx :-> Type variable `r' = r :: k0] [ 5077s] * In the type signature: [ 5077s] everything :: (r -> r -> r) -> GenericQ r -> GenericQ r [ 5077s] | [ 5077s] 116 | everything :: (r -> r -> r) -> GenericQ r -> GenericQ r [ 5077s] | ^^^^^^^^ [ 5077s] utils/check-api-annotations/ghc.mk:18: recipe for target 'utils /check-api-annotations/dist-install/build/Main.o' failed [ 5077s] make[1]: *** [utils/check-api-annotations/dist- install/build/Main.o] Error 1 [ 5077s] [ 5077s] utils/ghctags/Main.hs:61:36: error: [ 5077s] * GHC internal error: `FoundThing' is not in scope during type checking, but it passed the renamer [ 5077s] tcl_env of environment: [rCTr :-> ATcTyCon FileData :: *, [ 5077s] rCTs :-> APromotionErr RecDataConPE, [ 5077s] rCTw :-> ATcTyCon FileName :: *] [ 5077s] * In the type `[FoundThing]' [ 5077s] In the definition of data constructor `FileData' [ 5077s] In the data declaration for `FileData' [ 5077s] | [ 5077s] 61 | data FileData = FileData FileName [FoundThing] (Map Int String) [ 5077s] | ^^^^^^^^^^ [ 5077s] utils/ghctags/ghc.mk:18: recipe for target 'utils/ghctags/dist- install/build/Main.o' failed }}} Alpha 2 builds fine on PowerPC 64-bit little endian Linux. I am setting version to 8.5 as there is no tag for 8.6.1 alpha 2 yet. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15399> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15948: Hadrian cannot build on Windows
by GHC 10 Jan '19

10 Jan '19

#15948: Hadrian cannot build on Windows -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.8.1 Component: Build System | Version: 8.7 (Hadrian) | 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 Hadrian build on Windows currently fails with {{{ 'C:/msys64/home/ben/ghc/builds/0/project-0/_build/stage0/bin/ghc.exe' exited ghc.exe: could not detect mingw toolchain }}} when trying to build the RTS. I strongly suspect that the problem is that the stage1 toolchain built by Hadrian lives in `_build/stage0/bin/ghc` whereas the mingw tarballs were extracted to `inplace/mingw`. It's quite unclear to me how this ever worked. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15948> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15357: Make nofib suitable for runtime measurements.
by GHC 09 Jan '19

09 Jan '19

#15357: Make nofib suitable for runtime measurements. -------------------------------------+------------------------------------- Reporter: AndreasK | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.1 Component: NoFib | Version: 8.4.3 benchmark suite | 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: -------------------------------------+------------------------------------- Currently many benchmarks in a default nofib run have runtimes so low that they become meaningless. This comes with a bunch of issues: * It takes up build/runtime while not actually improving the accuracy of runtime measurements. * It skews results as the jump from 1ms to 2ms registers as a 200% change. * It can hide regression which fall outside of the measured granularity. * Higher number of runs per benchmark spend far too much time on the few slower benchmarks. At the extreme end there are 9 benchmarks with runtimes shorter than the granularity of 1ms. For some benchmarks changing this might be as easy as increasing the number of runs/iterations. For others changing problem sizes is not as easy since they process more complex input data. Below are the runtimes of a recent default nofib run. ||= benchmark =|| Time (ms) || || ansi || 0 || || awards || 0 || || banner || 0 || || calendar || 0 || || expert || 0 || || gen_regexps || 0 || || grep || 0 || || pretty || 0 || || scc || 0 || || cse || 1 || || eliza || 1 || || lift || 1 || || mkhprog || 1 || || prolog || 1 || || sorting || 1 || || veritas || 1 || || knights || 2 || || minimax || 2 || || x2n1 || 2 || || mandel2 || 3 || || parstof || 3 || || fluid || 4 || || pic || 4 || || boyer2 || 5 || || bspt || 5 || || cryptarithm2 || 5 || || fish || 6 || || gg || 6 || || reptile || 6 || || symalg || 6 || || tak || 6 || || VSD || 7 || || rfib || 7 || || queens || 9 || || rewrite || 9 || || sched || 11 || || fem || 12 || || fibheaps || 13 || || parser || 14 || || rsa || 14 || || genfft || 15 || || clausify || ansi || 0 || || awards || 0 || || banner || 0 || || calendar || 0 || || expert || 0 || || gen_regexps || 0 || || grep || 0 || || pretty || 0 || || scc || 0 || || cse || 1 || || eliza || 1 || || lift || 1 || || mkhprog || 1 || || prolog || 1 || || sorting || 1 || || veritas || 1 || || knights || 2 || || minimax || 2 || || x2n1 || 2 || || mandel2 || 3 || || parstof || 3 || || fluid || 4 || || pic || 4 || || boyer2 || 5 || || bspt || 5 || || cryptarithm2 || 5 || || fish || 6 || || gg || 6 || || reptile || 6 || || symalg || 6 || || tak || 6 || || VSD || 7 || || rfib || 7 || || queens || 9 || || rewrite || 9 || || sched || 11 || || fem || 12 || || fibheaps || 13 || || parser || 14 || || rsa || 14 || || genfft || 15 || || clausify || 17 || || gamteb || 17 || || fft || 18 || || boyer || 20 || || gcd || 20 || || sphere || 21 || || fft2 || 23 || || infer || 25 || || maillist || 25 || || mandel || 27 || || nucleic2 || 30 || || primes || 34 || || cichelli || 35 || || ida || 39 || || listcompr || 41 || || listcopy || 43 || || multiplier || 43 || || wang || 43 || || hpg || 45 || || anna || 46 || || reverse-complem || 46 || || integrate || 48 || || primetest || 50 || || paraffins || 54 || || solid || 54 || || puzzle || 55 || || treejoin || 61 || || compress2 || 64 || || compress || 65 || || event || 65 || || bernouilli || 74 || || comp_lab_zift || 78 || || simple || 86 || || wheel-sieve2 || 91 || || life || 100 || || exp3_8 || 102 || || wave4main || 103 || || typecheck || 106 || || atom || 110 || || fulsom || 112 || || CS || 116 || || para || 120 || || kahan || 138 || || transform || 145 || || power || 150 || || cacheprof || 151 || || hidden || 160 || || scs || 168 || || lcss || 175 || || wheel-sieve1 || 199 || || VS || 204 || || pidigits || 216 || || FS || 222 || || last-piece || 230 || || fasta || 263 || || cryptarithm1 || 264 || || CSD || 272 || || digits-of-e1 || 273 || || binary-trees || 342 || || digits-of-e2 || 381 || || circsim || 418 || || S || 451 || || VSM || 497 || || lambda || 617 || || integer || 905 || || n-body || 1043 || || linear || 1070 || || spectral-norm || 1132 || || constraints || 1171 || || exact-reals || 1289 || || mate || 1955 || || fannkuch-redux || 2185 || || k-nucleotide || 2989 || || 17 || || gamteb || 17 || || fft || 18 || || boyer || 20 || || gcd || 20 || || sphere || 21 || || fft2 || 23 || || infer || 25 || || maillist || 25 || || mandel || 27 || || nucleic2 || 30 || || primes || 34 || || cichelli || 35 || || ida || 39 || || listcompr || 41 || || listcopy || 43 || || multiplier || 43 || || wang || 43 || || hpg || 45 || || anna || 46 || || reverse-complem || 46 || || integrate || 48 || || primetest || 50 || || paraffins || 54 || || solid || 54 || || puzzle || 55 || || treejoin || 61 || || compress2 || 64 || || compress || 65 || || event || 65 || || bernouilli || 74 || || comp_lab_zift || 78 || || simple || 86 || || wheel-sieve2 || 91 || || life || 100 || || exp3_8 || 102 || || wave4main || 103 || || typecheck || 106 || || atom || 110 || || fulsom || 112 || || CS || 116 || || para || 120 || || kahan || 138 || || transform || 145 || || power || 150 || || cacheprof || 151 || || hidden || 160 || || scs || 168 || || lcss || 175 || || wheel-sieve1 || 199 || || VS || 204 || || pidigits || 216 || || FS || 222 || || last-piece || 230 || || fasta || 263 || || cryptarithm1 || 264 || || CSD || 272 || || digits-of-e1 || 273 || || binary-trees || 342 || || digits-of-e2 || 381 || || circsim || 418 || || S || 451 || || VSM || 497 || || lambda || 617 || || integer || 905 || || n-body || 1043 || || linear || 1070 || || spectral-norm || 1132 || || constraints || 1171 || || exact-reals || 1289 || || mate || 1955 || || fannkuch-redux || 2185 || || k-nucleotide || 2989 || -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15357> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14271: ghci hangs with -fexternal-interpreter -prof
by GHC 09 Jan '19

09 Jan '19

#14271: ghci hangs with -fexternal-interpreter -prof ----------------------------------------+------------------------------- Reporter: AndreasK | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.2.1 Keywords: | Operating System: Windows Architecture: Unknown/Multiple | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+------------------------------- {{{ ghci -fexternal-interpreter -prof GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Access violation in generated code when reading 00000001001e0418 }}} * The address remains the same between reruns (and reinstalls) of ghc. * Closing the hanging process leaves the launched ghc active in the background. * The directory I launch ghci from doesn't seem to matter. * I have only tried it on my desktop so far (Win10/Skylake) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14271> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15938: Hadrian's recompilation check is extremely slow
by GHC 09 Jan '19

09 Jan '19

#15938: Hadrian's recompilation check is extremely slow -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.8.1 Component: Build System | Version: 8.6.2 (Hadrian) | 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: -------------------------------------+------------------------------------- I just Ctrl-C'd hadrian while it was building `libraries/base`, having noticed that I forgot to start it with `-j`. I then immediately restarted it and noticed that Hadrian needed to think for 45 seconds before it started even a single build. This is orders of magnitude worse than `make` so something must be wrong. I'm setting this at high priority since 45 seconds is longer than many complete `make` rebuilds. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15938> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14576: Internal error when compiling TH code with profiling on Windows
by GHC 09 Jan '19

09 Jan '19

#14576: Internal error when compiling TH code with profiling on Windows -------------------------------------+------------------------------------- Reporter: lazac | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHC API | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- When using the GHC API with this minimal example, compiled with profiling enabled: {{{#!hs module Main where import GHC import GHC.Paths ( libdir ) main = runGhc (Just libdir) $ do env <- getSession dflags <- getSessionDynFlags setSessionDynFlags dflags target <- guessTarget "A.hs" Nothing setTargets [target] load LoadAllTargets }}} Invoking the main executable: {{{ testprof }}} While A.hs contains a TH splice: {{{#!hs {-# LANGUAGE TemplateHaskell #-} module A where $(return []) }}} The compiler crashes: {{{ testprof.exe: internal error: IMAGE_REL_AMD64_ADDR32[NB]: High bits are set in 10e6109d0 for .text (GHC version 8.2.1 for x86_64_unknown_mingw32) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. }}} The walkaround is to use -fexternal-interpreter, in that case, the crash does not happen. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14576> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15578: Honour INLINE pragmas on 0-arity bindings
by GHC 08 Jan '19

08 Jan '19

#15578: Honour INLINE pragmas on 0-arity bindings -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 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: -------------------------------------+------------------------------------- Currently if we see {{{ x = factorial 200 {-# INLINE x #-} f y = ...x... }}} we won't inline `x`, lest we duplicate the work of `factorial 200`. But * Occasionally it's very important to inline `x`: see Trac #15519 for a real-world example. * Suppose `x` is used exactly once, not inside a lambda, thus {{{ x = blah {-# INLINE x #-} g = ...x... }}} Then, if there is ''no'' INLINE pragma, `x` will get inlined (by `preInlineUnconditionally`. But if there ''is'' an INLINE pragma, currently `x` is ''not'' inlined by `preInlineUnconditionally`: see `Note [Stable unfoldings and preInlineUnconditionally]` in `SimplUtils`. This is insane! * INLINE says "inline me at every saturated call", where "saturated" is determined by the number of arguments syntactically to the left of the "=" in the source bindings. In this case, there are no arguments to the left, so every occurrence is saturated. So it's inconsistent not to inline. Bottom line: if a 0-ary binding has an INLINE pragma, I think we should inline it at every use site * Regardless of the work duplication * Including inside lambdas Note, however, that there is a real risk that full laziness will float it right back out again. Consider again {{{ x = factorial 200 {-# INLINE x #-} f y = ...x... }}} After inlining we get {{{ f y = ...(factorial 200)... }}} but it's entirely possible that full laziness will do {{{ lvl23 = factorial 200 f y = l...lvl23... }}} That's a problem for another day. Presumably the reason the user wanted to inline it was to get some rule to fire, and this change gives at least some chance that will happen, and makes INLINE behave consistently. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15578> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13962: GHCi allows unsaturated type family
by GHC 08 Jan '19

08 Jan '19

#13962: GHCi allows unsaturated type family -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) 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: -------------------------------------+------------------------------------- Taken from [http://ics.p.lodz.pl/~stolarek/_media/pl:research:promotion- haskell14-slides.pdf Promoting Functions to Type Families in Haskell] {{{#!hs {-# Language TypeFamilies, PolyKinds, DataKinds, TypeOperators #-} type family Map (f :: a -> b) (xs :: [a]) :: [b] where Map f '[] = '[] Map f (x ': xs) = f x ': Map f xs data N = O | S N type family Pred (n :: N) :: N where Pred O = O Pred (S n) = n -- The type family ‘Map’ should have 2 arguments, but has been given 1 type MapPred = Map Pred }}} fails as expected, but it works in GHCi {{{ ghci> :kind Map Pred Map Pred :: [N] -> [N] ghci> :kind! Map Pred '[S (S O), S O, O] Map Pred '[S (S O), S O, O] :: [N] = '['S 'O, 'O, 'O] }}} I can only test this in GHC 7.8, 8 now. I know GHCi has weird rules for unsaturated type families but I figured I'd write a ticket because the slides say "But it is invalid to write: `Map Pred '[O, S O]`". -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13962> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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