empty list bug?

Ralf Hinze ralf@informatik.uni-bonn.de
Mon, 04 Jun 2001 17:12:43 +0200


Dear Ernest,

this is my favourite Hugs `bug'. For an explanation see Simon Thompson'
page
on Some common (and not so common!) Hugs errors, cf `reverse []'.

Cheers, Ralf

> Sirs/Mesdames:
> 
> We are considering a course using Haskell. We have "Hugs 98: Based on the
> haskell 98 standard Copyright 1994-2001,"
> downloaded just a few months ago. (This is under Windows NT.) The following
> puzzles us --
> 
> From the prelude:
>         take 1 [ ]   --   expected to return the empty list [ ], instead
> gives error message:
>         ERROR - Cannot find "show" function for:
>         ***  Expression : take 1 [ ]
>         ***  Of type            : [a]