[mercury-users] higher order modes

[Michael Day]

If I try to return a det predicate where a semidet one is expected I get a
nasty and rather unobvious mode error. This can be avoided by promoting
(or demoting?) the predicate explicitly with a lambda expression:

	SemiThing = (pred(...) :- DetThing)

Is there any reason the compiler can't do this by itself?

Michael

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