- (prefix,suffix) = case break (== '.') $ reverse template of
- (rev_suffix, rev_prefix) ->
- (reverse rev_prefix, reverse rev_suffix)
+ (prefix,suffix) =
+ case break (== '.') $ reverse template of
+ -- First case: template contains no '.'s. Just re-reverse it.
+ (rev_suffix, "") -> (reverse rev_suffix, "")
+ -- Second case: template contains at least one '.'. Strip the
+ -- dot from the prefix and prepend it to the suffix (if we don't
+ -- do this, the unique number will get added after the '.' and
+ -- thus be part of the extension, which is wrong.)
+ (rev_suffix, '.':rest) -> (reverse rest, '.':reverse rev_suffix)
+ -- Otherwise, something is wrong, because (break (== '.')) should
+ -- always return a pair with either the empty string or a string
+ -- beginning with '.' as the second component.
+ _ -> error "bug in System.IO.openTempFile"