Re: As- and irrefutable- patterns

[S. Alexander Jacobson]

Presumably @~ is an undefined operator, but haskell tries to resolve the
type of foo before resolving the type of @~.

-Alex-

On Wed, 25 Aug 1999, Keith Wansbrough wrote:

> According to the Haskell 98 report, patterns have the following grammar:
> 
> apat ::= var [ @ apat ]
>       |  ~ apat
>       | ...etc...
> 
> Thus the following program should be legal (IMHO):
> 
> main = let foo@~(x,y) = (1,2)
>        in  print foo
> 
> Instead, both Hugs and GHC report
> 
>   ERROR "TestAsPat.hs" (line 1): Undefined variable "foo"
> 
> What have I missed?
> 
> Replacing the lhs with foo@(~(x,y)) works, BTW.
> 
> Thanks..
> 
> --KW 8-)
> 
> 
> -- 
> : Keith Wansbrough, MSc, BSc(Hons) (Auckland) ------------------------:
> : PhD Student, Computer Laboratory, University of Cambridge, England. :
> :  (and recently of the University of Glasgow, Scotland. [><] )       :
> : Native of Antipodean Auckland, New Zealand: 174d47' E, 36d55' S.    :
> : http://www.cl.cam.ac.uk/users/kw217/  mailto:[EMAIL PROTECTED]     :
> :---------------------------------------------------------------------:
> 
> 

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