PrelTup

1998-04-20 Thread Manuel Chakravarty
Hi Glaswegians, [This is not necessarily a bug; nevertheless, any advice would be appreciated.] During linking of a (big) Happy generate file, I ended up with a linker message like KCParser.o(.text+0x41a9f): undefined reference to

Re: Confusing error message

1998-02-18 Thread Manuel Chakravarty
I encountered a confusing error message, which you can reproduce with type P a = Maybe a instance Monad P where (=) = error "foo" return = error "bar" I get bug.hs:5: `P' should have 1 argument, but has been given 0 . Would it be better if it said

Confusing error message

1998-02-17 Thread Manuel Chakravarty
Hi GHC-Developers! I encountered a confusing error message, which you can reproduce with type P a = Maybe a instance Monad P where (=) = error "foo" return = error "bar" I get bug.hs:5: `P' should have 1 argument, but has been given 0 . with ** ghc 2.05 ** (maybe

Buggy derived instance of Show

1998-01-29 Thread Manuel Chakravarty
Dear GHC Bug Hunters, I found a bug in derived instances for Show that contain `Float' numbers. Running data MassPnt = MassPnt Float (Float, Float) deriving (Show) main = do print 1.18088e+11 let p = MassPnt 1.18088e+11 (-0.768153, -0.742202)

Floats don't like to be referenced [was: Buggy derived instance of Show]

1998-01-29 Thread Manuel Chakravarty
Scary, but true...the floats in my version of ghc don't like to be referenced. The program data MassPnt = MassPnt Float (Float, Float) deriving (Show) main = do print 1.18088e+11-- (1) let x = 1.18088e+11

Misleading error message

1998-01-13 Thread Manuel Chakravarty
I just encountered a misleading errors message produced during type checking of `case' expressions. Given the malformed program test = case [] of (a, b) - 1 test2 = case [] of [] - 1:() I get the following error messages bug.hs:8: Couldn't match the type

Re: ghc Diagnostics

1997-10-14 Thread Manuel Chakravarty
Simon Marlow wrote: I take your point that this isn't very consistent: there should be a way to turn off all warnings easily. What do other people think? The options are: * have all warnings off by default, a standard set of warnings being available by adding the -W

Re: GHC status

1997-07-24 Thread Manuel Chakravarty
I read a nice paper recently "The cathedral and the bazaar" by Eric Raymond, reflecting on his experience Linux, and in particular of developing "fetchmail". You can find it at http://locke.ccil.org/~esr/writings/cathedral.html It's really worth reading. One particular thing he

Re: A new view of guards

1997-04-29 Thread Manuel Chakravarty
I would really welcome feedback on this proposal. Have you encountered situations in which pattern guards would be useful? Can you think of ways in which they might be harmful, or in which their semantics is non-obvious? Are there ways in which the proposal could be improved? And so on.

fixpoint combinator in monads

1996-07-22 Thread Manuel Chakravarty
Hi! For monads like the `IO' monad, is there any reason for not providing a monad operator wrapping the fixpoint combinator into the monad? I mean a function fixM :: (a - M a) - M a for some monad `M', which feeds its argument the result eventually produced by the overall monadic

Haskell 1.3: modules module categories

1995-09-30 Thread Manuel Chakravarty
Hi! Talking to a friend, who is project manager in a software company, about modules for Haskell, he made two comments that may be of interest to the current discussion. (1) With regard to the idea of 99% hand-written interfaces (just mark everthing that should go into the interface in a