SWI-Prolog -- mapsubterms

Availability::- use_module(library(terms)).(can be autoloaded)

[det]mapsubterms(:Goal, +Term1, -Term2)

[det]mapsubterms_var(:Goal, +Term1, -Term2)

Recursively map sub terms of Term1 into subterms of Term2 for every pair for which call(Goal, ST1, ST2) succeeds. Procedurably, the mapping for each (sub) term pair T1/T2 is defined as:

If T1 is a variable
- mapsubterms/3 unifies T2 with T1.
- mapsubterms_var/3 treats variables as other terms.
If call(Goal, T1, T2) succeeds we are done. Note that the mapping does not continue in T2. If this is desired, Goal must call mapsubterms/3 explicitly as part of its conversion.
If T1 is a dict, map all values, i.e., the tag and keys are left untouched.
If T1 is a list, map all elements, i.e., the list structure is left untouched.
If T1 is a compound, use same_functor/3 to instantiate T2 and recurse over the term arguments left to right.
Otherwise T2 is unified with T1.

Both predicates are implemented using foldsubterms/5.