On Mon, 4 Aug 2003 10:01:50 +0000
"Thomas L. Bevan"
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Is there any reason why show :: String -> String is not equivalent to 'id' ?
Because I believe the intent (the Report may make some mention of this) is that read . show should be id. Either way, you aren't strongly exercising the function. What about show "\"" which is """ or show "\0\r\n" and other such examples? This wouldn't be the right result for many uses.
At the moment,
show "one" = "\"one\""
which leads to problems because it often requires String to be treated as a special case, rather than just a member of Show.
Tom
Having show :: String -> String be id would be making a special case the other way. Perhaps the sensible thing to do is make your own class say Display, e.g. class Display a where display :: a -> String This would be a class for displaying values rather than something more akin to textual serialization that Show is. You can go further and make a pretty printing class, or a less flexibly, but a little more conveniently is class Show a => Display a where display :: a -> String display = show So that you can just have, instance Display Bool instance Display Int, etc. with instance Display String where display = id