[mercury-users] append for list skeletons

[Robert Colvin]

Hi, I just wanted to check that I understand the manual - it says that it is
not possible to implement append(in_listskel, in_listskel, out_listskel),
ie where the lists are lists of uninstantiated variables.  Therefore the
naive/inefficient implementation of reverse

rev([], []).
rev([H|T], R) :- 
    append(RT, [H], R), rev(T, RT).

will not be implementable for list skeletons?

Thanks,
Rob

ps.- thanks Robert and Richard for help with natural numbers last week

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