File "hiord"

This file introduces higher order logic programming to the Dogelog Player Prolog system, in that we support the predicates call/n. The predicates are not realized inside the Novacore, but have to be explicitly requested through this file. The predicates call/n are provided for the arities n = 2..8, the minimum required by the ISO core Prolog standard.

The predicates maplist/n and foldl/n apply a closure on the members of a list. Thus freeing the end-user from writing the boiler plate code of a loop. This allows for set oriented processing of lists without the need for backtracking. The drawback is increased use of memory, since the lists are materialized.

The following hiord predicates are provided:

numbervars(X, N, M):

The predicate succeeds in M with the next index after numbering all variables in X starting with index N.

unnumbervars(S, N, T):

The predicate succeeds in T with a copy of S with the numbering greater or equal than N replaced by variables.

maxvars(T, M):

The predicate succeeds in M with the max numbering of the term X.

free_variables(Q, L, G): [ISO 7.1.1.4]

The predicate succeeds in L with the free variabes of Q and in G with the quantifier free of Q.

call(F, A1, .., An): [Corr.2 8.15.4.4]

The predicate succeeds in calling the goal which results from appending the arguments A1, .., An to the callable F.

maplist(C, L1, .., Ln): [N235 7.4]

The predicate succeeds whenever the closure C can be applied to each of the joint elements X1, .., Xn in the lists L1, .. Ln.

foldl(C, L1, .., Ln, I, O):

The predicate succeeds in O with the closure C chained through the elements X1, .., Xn of the lists L1, .. Ln starting with I.

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