tphyahoo wrote:
>
> "Issues: In Haskell, any function or constructor can be enclosed in backticks
> and then used as an infix operator. "
>
> from http://www-users.cs.york.ac.uk/~mfn/hacle/issues/node2.html
>
> But this seems to be contradicted by...
>
> from #haskell
>
> -- 09:19 < tphyahoo> > let func = (+) in 1 `func` 2
> -- 09:19 < lambdabot> 3
> -- 09:20 < tphyahoo> but ......
> -- 09:20 < tphyahoo> 1 `(+)` 2
> -- 09:20 < tphyahoo> > 1 `(+)` 2
> -- 09:20 < lambdabot> Parse error
>
> (+) is a function, is it not?
>
> Where's the rub?
The thing inside the backticks has to be a syntatic name, not an
expression. The grammar from the Haskell Report
( http://www.haskell.org/onlinereport/syntax-iso.html )...
varid -> (small {small | large | digit | ' })<reservedid>
conid -> large {small | large | digit | ' }
varop -> varsym | `varid ` (variable operator)
qvarop -> qvarsym | `qvarid ` (qualified variable operator)
conop -> consym | `conid ` (constructor operator)
qconop -> gconsym | `qconid ` (qualified constructor operator)
...I've also thought it would be nice to be able to say things like...
(foo `liftM2 (,)` bar)
Greg Buchholz
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