True if conjunction of results is true. Unlike forall/2,
which runs a failure-driven loop that proves Goal for each
solution of
Generator, foreach/2
creates a conjunction. Each member of the conjunction is a copy of Goal,
where the variables it shares with Generator are filled with
the values from the corresponding solution.
The implementation executes forall/2
if Goal does not contain any variables that are not shared
with Generator.
Here is an example:
?- foreach(between(1,4,X), dif(X,Y)), Y = 5.
Y = 5.
?- foreach(between(1,4,X), dif(X,Y)), Y = 3.
false.
- bug
- Goal is copied repeatedly, which may cause problems if
attributed variables are involved.
foreach(:Generator,
:Goal)