[Haskell-cafe] IO () and IO [()]

Neil Mitchell ndmitchell at gmail.com
Mon Mar 10 19:24:39 EDT 2008


> I understand the lack of distinction between a unit type and a 0-tuple,
>  since they are isomorphic.

It's more we pronounce 0-tuple as unit, they are identical.

>  But it is strange that there is no 1-tuple,
>  since _|_ and the 1-tuple (_|_) would be different things entirely, no?

Yes, it would be useful, but what would the syntax be? (x) already
means something else - namely grouping. Yhc defines both Tuple1 and
_E, both of which are the 1-tuple. I'd like it if there was a standard
definition Box for the 1-tuple, in the base libraries.



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