Undefined variable bug

If I load a file Test.hs containing only the line

  tst = isAlpha

into the Feb2001 version of Hugs on RedHat then it works fine, but
when I load it into the up-to-date Nov2003 version on Debian, I get

Prelude> :l Test
ERROR "/Test.hs":1 - Undefined variable "isAlpha"

But isAlpha should be known; I can do

Prelude> :t isAlpha
isAlpha :: Char -> Bool

any ideas why isAlpha becomes unknown in the Nov2003 hugs?

regards,

%!PS                       %  -John Tromp (http://www.cwi.nl/~tromp/)
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