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[GHC] #7876: hClose002 for ghci hangs on Mac OS X
by GHC 01 May '13

01 May '13

#7876: hClose002 for ghci hangs on Mac OS X ----------------------------------------+----------------------------------- Reporter: nfrisby | Owner: Type: bug | Status: new Priority: normal | Component: Compiler Version: 7.6.3 | Keywords: Os: MacOS X | Architecture: Unknown/Multiple Failure: Incorrect result at runtime | Blockedby: Blocking: | Related: ----------------------------------------+----------------------------------- I'm on 10.7.5 ghc : ade1ae97ed52c493ec415c1601dace39b64071dd testsuite : 743cab5865ae0b9820dadc33a692511e0e467b9b base : b3387abfbc94b69e977c232386acad4dde7597e8 When I validate, hClose002 hangs. If I execute the hClose002 program, I get what seems to be the expected output. If I run the script through ghci, it hangs. The test opens a file in WriteMode, closes it "without telling the IO library", then hCloses it twice. Then it does that again in ReadMode. Thus there are four hClose calls in total. It is the third one that hangs. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7876> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4466: Add extension for type application
by GHC 30 Apr '13

30 Apr '13

#4466: Add extension for type application ---------------------------------+------------------------------------------ Reporter: igloo | Owner: Type: feature request | Status: new Priority: low | Milestone: 7.6.2 Component: Compiler | Version: 6.12.3 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: | Testcase: Blockedby: | Blocking: Related: | ---------------------------------+------------------------------------------ Changes (by kosmikus): * cc: mail@… (added) -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4466#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5296: Add explicit type applications
by GHC 30 Apr '13

30 Apr '13

#5296: Add explicit type applications ----------------------------------------+----------------------------------- Reporter: dsf | Owner: Type: feature request | Status: new Priority: low | Milestone: 7.6.2 Component: Compiler (Type checker) | Version: 7.0.3 Keywords: | Os: Linux Architecture: x86_64 (amd64) | Failure: GHC rejects valid program Difficulty: | Testcase: Blockedby: 1897 | Blocking: Related: | ----------------------------------------+----------------------------------- Changes (by kosmikus): * cc: mail@… (added) -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5296#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5296: Add explicit type applications
by GHC 30 Apr '13

30 Apr '13

#5296: Add explicit type applications ----------------------------------------+----------------------------------- Reporter: dsf | Owner: Type: feature request | Status: new Priority: low | Milestone: 7.6.2 Component: Compiler (Type checker) | Version: 7.0.3 Keywords: | Os: Linux Architecture: x86_64 (amd64) | Failure: GHC rejects valid program Difficulty: | Testcase: Blockedby: 1897 | Blocking: Related: | ----------------------------------------+----------------------------------- Changes (by sweirich): * cc: sweirich@… (added) -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5296#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4466: Add extension for type application
by GHC 30 Apr '13

30 Apr '13

#4466: Add extension for type application ---------------------------------+------------------------------------------ Reporter: igloo | Owner: Type: feature request | Status: new Priority: low | Milestone: 7.6.2 Component: Compiler | Version: 6.12.3 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: | Testcase: Blockedby: | Blocking: Related: | ---------------------------------+------------------------------------------ Changes (by sweirich): * cc: sweirich@… (added) -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4466#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #7868: Enable -funbox-strict-small-fields by default
by GHC 30 Apr '13

30 Apr '13

#7868: Enable -funbox-strict-small-fields by default -----------------------------+---------------------------------------------- Reporter: tibbe | Owner: Type: feature request | Status: new Priority: normal | Component: Compiler Version: 7.7 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: -----------------------------+---------------------------------------------- See discussion at http://www.haskell.org/pipermail/ghc- devs/2013-April/001109.html Summary from the commit message: {{{ Enable -funbox-small-strict-fields by default The flag shows no real impact on nofib benchmarks and GHC itself, which is expected given the small number of strict but not already unpacked fields in the source of these programs. However, the flag allows us to omit most of the UNPACK pragmas that are so common in source code today. }}} -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7868> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #7869: GHC complains about applying a function to one argument
by GHC 30 Apr '13

30 Apr '13

#7869: GHC complains about applying a function to one argument -----------------------------+---------------------------------------------- Reporter: Mortchek | Owner: Type: bug | Status: new Priority: normal | Component: Compiler Version: 7.4.2 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: -----------------------------+---------------------------------------------- When this function is compiled: {{{ let f = (\x -> f x) :: [a] -> b }}} GHC gives this error message: {{{ Foo.hs:1:12: Couldn't match type `b' with `b1' `b' is a rigid type variable bound by the inferred type of f :: [a] -> b at Foo.hs:1:1 `b1' is a rigid type variable bound by an expression type signature: [a1] -> b1 at Foo.hs:1:5 Expected type: [a1] -> b1 Actual type: [a] -> b The function `f' is applied to one argument, but its type `[a] -> b' has only one In the expression: f x In the expression: (\ x -> f x) :: [a] -> b Foo.hs:1:12: Couldn't match type `a' with `a1' `a' is a rigid type variable bound by the inferred type of f :: [a] -> b at Foo.hs:1:1 `a1' is a rigid type variable bound by an expression type signature: [a1] -> b1 at Foo.hs:1:5 Expected type: [a1] -> b1 Actual type: [a] -> b The function `f' is applied to one argument, but its type `[a] -> b' has only one In the expression: f x In the expression: (\ x -> f x) :: [a] -> b }}} The erroneous part is: {{{ The function `f' is applied to one argument, but its type `[a] -> b' has only one In the expression: f x In the expression: (\ x -> f x) :: [a] -> b }}} This error message should not be present, as applying a function to one argument is not a problem. This happens in GHCi as well. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7869> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7473: getModificationTime gives only second-level resolution
by GHC 30 Apr '13

30 Apr '13

#7473: getModificationTime gives only second-level resolution ----------------------------------+----------------------------------------- Reporter: duncan | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.8.1 Component: libraries/directory | Version: 7.6.1 Resolution: | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: ----------------------------------+----------------------------------------- Comment(by refold): I've added a version of Neil's code to Cabal: https://github.com/haskell/cabal/blob/master/cabal- install/Distribution/Compat/Time.hs#L58 Perhaps it can be reused for `directory`. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7473#comment:6> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #7856: Wrong error message for unknown Instance
by GHC 30 Apr '13

30 Apr '13

#7856: Wrong error message for unknown Instance ----------------------------------------------+----------------------------- Reporter: bas | Owner: Type: feature request | Status: new Priority: normal | Component: Compiler (Type checker) Version: 7.6.3 | Keywords: Instance Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: Incorrect warning at compile-time | Blockedby: Blocking: | Related: ----------------------------------------------+----------------------------- This type-incorrect program gives a wrong error message: {{{ main = tmp "hello" where tmp :: String -> IO () tmp = sequence_ lst lst = [putStrLn "hi"] }}} Namely: {{{ Couldn't match expected type `IO ()' with actual type `()' Expected type: String -> IO () Actual type: String -> () In the return type of a call of `sequence_' In the expression: sequence_ lst }}} I would not expect the "actual type" to be "String -> ()", but rather "IO ()". Note: GHC expects that "(->) String" is a monad. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7856> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #7851: Give better diagnostic when arguments are omitted to a function call in do-notation
by GHC 30 Apr '13

30 Apr '13

#7851: Give better diagnostic when arguments are omitted to a function call in do- notation ----------------------------------------------+----------------------------- Reporter: JohnWiegley | Owner: Type: feature request | Status: new Priority: normal | Component: Compiler (Parser) Version: 7.4.2 | Keywords: Os: MacOS X | Architecture: x86_64 (amd64) Failure: Incorrect warning at compile-time | Blockedby: Blocking: | Related: ----------------------------------------------+----------------------------- When using any Monad other than (->) e, it is almost always an error for a function call to yield another function, rather than a monadic value. For example: import Control.Monad.Trans.State main = flip runStateT 10 $ do print print "Hello" The error you get from this code is (with GHC 7.4.2): Couldn't match expected type `StateT b0 m0 a0' with actual type `a1 -> IO ()' While this is fully correct, I think the compiler could do much better. The fact that the naked call to "print" doesn't return an IO value, but rather a function type, could be immediately detected as an error, allowing GHC to say something like: Detected function type (a -> IO ()) returned when IO () was expected, perhaps missing an argument in call to "print"? My example with StateT, IO and print is rather trivial, but when you start getting into nested monad transformers, in polymorphic functions where the transformer and underlying monad types are parameterized, the errors from GHC become downright mysterious. Only through experience have I become able to read them as saying "You've forgotten an argument in your call to f". Since I can't think of a case (outside the function monad), where statements within a do-notation block should yield a function type rather than a monadic value appropriate to that Monad, perhaps we could do better here in guiding the user to the real source of the problem. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7851> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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