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maplist(+Pred, ?OldList, ?NewList)
Succeeds if Pred(Old, New) succeeds for corresponding pairs of elements
from OldList and NewList.
- +Pred
- Atom or compound term.
- ?OldList
- List or variable.
- ?NewList
- List or variable.
Description
Either OldList or NewList should be a proper list. maplist/3 succeeds
if for every corresponding pair of elements Old, New of the two lists
OldList and NewList the invocation of Pred with two aditional arguments
Old and New succeeds.
The definition of this Prolog library predicate is:
:- tool(maplist/3, maplist_body/4).
maplist_body(_, [], [], _).
maplist_body(Pred, [H1|T1], [H2|T2], M) :-
Pred =.. PL,
append(PL, [H1, H2], NewPred),
Call =.. NewPred,
call(Call, M),
maplist_body(Pred, T1, T2, M).
The following should be noted:
1. This predicate does not perform any type testing functions.
2. This predicate is not protected by ECLiPSe and may be redefined without
generating a warning message.
Fail Conditions
Fails if at least for one pair of corresponding elements of OldList and
NewList the invocation of Pred with these two additional arguments
fails.
Resatisfiable
No.
Exceptions
Examples
Success:
maplist(integer_atom, [1, 2, 3], ['1', '2', '3']).
maplist(sin, [0, 1, 2], X).
(gives X = [0.0, 0.841471, 0.909297])
maplist(get_flag(var/1), [skip, type, spy], [off, built_in, off]).
Fail:
maplist(type_of, [1, a, "a"], [integer, atom, atom]).
See Also
checklist / 2