11.2.4 Control

:P,:Q ISO
prove P and Q
:P;:Q ISO
prove P or Q
+M::P ISO
call P in module M
:P->:Q;:R ISO
if P succeeds, prove Q; if not, prove R
:P->:Q ISO
if P succeeds, prove Q; if not, fail
! ISO
cut any choices taken in the current procedure
\+ :P ISO
goal P is not provable
?X ^ :P
there exists an X such that P is provable (used in setof/3 and bagof/3)
block :P declaration
declaration that predicates specified by P should block until sufficiently instantiated
call(:P) ISO
call(:P,...)
execute P or P(...)
call_cleanup(:Goal,:Cleanup)
Executes the procedure call Goal. When Goal succeeds determinately, is cut, fails, or raises an exception, Cleanup is executed.
call_residue_vars(:Goal,?Vars)
Executes the procedure call Goal. Vars is unified with the list of new variables created during the call that remain unbound and have blocked goals or attributes attached to them.
+Iterators do :Body
executes Body iteratively according to Iterators
fail ISO
fail (start backtracking)
false
same as fail
freeze(+Var,:Goal)
Blocks Goal until nonvar(Var) holds.
if(:P,:Q,:R)
for each solution of P that succeeds, prove Q; if none, prove R
once(:P) ISO
Find the first solution, if any, of goal P.
otherwise
same as true
repeat ISO
succeed repeatedly on backtracking
true ISO
succeed
when(+Cond,:Goal)
block Goal until Cond holds

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