Package: ghc6
Version: 6.8.2-6
Severity: wishlist
If I ask ghc to interpret a higher-rank function type, I get this
error:
Prelude> :t undefined :: ((forall a . a -> a) -> a -> a)
<interactive>:1:24:
Illegal operator `.' in type `forall a . (a -> a)'
(Use -XTypeOperators to allow operators in types)
If I turn on -XExistentialQuantification, I get this one instead:
Prelude> :t undefined :: ((forall a . a -> a) -> a -> a)
<interactive>:1:0:
Illegal polymorphic or qualified type: forall a. a -> a
In an expression type signature:
(forall a. a -> a) -> a -> a
It might not be possible in the first case (where forall isn't a
keyword), but in the second case it would be nice if ghc could detect
my attempt to enter a higher-rank type and suggest the appropriate
extension. (-XRankNTypes)
Daniel
-- System Information:
Debian Release: lenny/sid
APT prefers unstable
APT policy: (500, 'unstable')
Architecture: i386 (i686)
Kernel: Linux 2.6.26-1-686 (SMP w/2 CPU cores)
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Shell: /bin/sh linked to /bin/bash
Versions of packages ghc6 depends on:
ii gcc 4:4.3.2-1 The GNU C compiler
ii haskell-utils 1.11 Utilities used by the Debian Haske
ii libc6 2.7-13 GNU C Library: Shared libraries
ii libgmp3-dev 2:4.2.2+dfsg-3 Multiprecision arithmetic library
ii libgmp3c2 2:4.2.2+dfsg-3 Multiprecision arithmetic library
ii libncurses5 5.6+20080907-1 shared libraries for terminal hand
ii libreadline5 5.2-3 GNU readline and history libraries
ii libreadline5-dev 5.2-3 GNU readline and history libraries
ii perl [perl5] 5.10.0-14 Larry Wall's Practical Extraction
ghc6 recommends no packages.
Versions of packages ghc6 suggests:
ii ghc6-doc 6.8.2-6 Documentation for the Glasgow Hask
pn ghc6-prof <none> (no description available)
pn haskell-doc <none> (no description available)
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