As of at least recently, empty cases are entirely permitted (and used for e.g. Void / nullary types).
> The rule "alt" allows "(empty alternative)"
Ah, yes. But no? The standard says
> A case expression must have at least one alternative
> and each alternative must have at least one body.
Should this be "each non-empty alternative must have ..."?
I think the intention is to allow
case () of () | False -> () | True -> ()
(one alternative, two bodies) but to disallow
case () of ()
(one alternative, no body)
- J.
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