Simon Marlow writes:
> Alex Ferguson <[EMAIL PROTECTED]> writes:
>
> > Is pattern-matching short strings (one or two characters) likely to be
> > _vastly_ less efficient than matching against a single level of
> > constructor? (Order of magnitude, plus.) Trying to make sense of some
> > profiling numbers, here...
>
> Quite possibly - pattern matching on strings involves building a
> dictionary for Eq [Char], unpacking the string (it's represented as
> packed in the object code), and performing the comparison. This is
> probably bad.
>
This is not always the case, string literals of length 0 and 1 are
expanded into list form, so
f "a" =
f ...
and
f ('a':[]) =
f ...
should generate the same pattern matching code.
--Sigbjorn
