Re: Higher order programming: apply/3 implemented in swi

On 2008-05-18, levilista@xxxxxxxxx <levilista@xxxxxxxxx> wrote:
On May 18, 10:55 am, Jan Wielemaker <j...@xxxxxxxxxxxxxxxxxxx> wrote:

<snip>

apply(F,Args,Term) :-
F =.. List,
append(List, Args, All),
Term =.. All.

Cheers --- Jan

When using the lambda notation in functional languages, we can create
semi substituted functions. In prolog its equivalent is a predicate
with incorrect arity. Calling it will give us errors. apply/2 calls it
prematurely, that's the problem.

That is an answer on why you sometimes need apply/3 (true, sometimes you
wish to extend the arguments without making the call; for example DCG
translation does this).

Still, I don't see where your code is different in functionality from
the trivial code above. Ok, my code creates two intermediate lists that
can be avoided at the cost of a bit more programming, but your code
creates even more intermediate datastructures.

--- Jan

.

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