expression - Prolog - How can obtain the prefix form of a math calculation given its usual form? -


i'm new in prolog , program calculator. need program predicate process given arithmetic expression, written in usual form (infix form), such obtain prefix form. elements of expression grouped sublists 3 elements, of following form [operator, term1, term2], such terms can in turn lists. predicate called parse should defined , work in example:

?-parse([1,+,2,*,3],pf). pf=[+,1,[*,2,3]]

you may use atom_to_term/3 , =../2 obtain prefix form of arithmetic expression. atomic_list_concat/2 create atom input list, atom_to_term build term (which infix representation of arithmetic expression). then, using univ (=..), can recursively obtain prefix notation.

i.e.:

parse(lexp, pf):-   atomic_list_concat(lexp, exp),   atom_to_term(exp, term, _),   parse1(term, pf).  parse1(term, pf):-   term =.. [pf]. parse1(term, [op, left, right]):-   term =.. [op, tleft, tright],   parse1(tleft, left),   parse1(tright, right).

test case:

?- parse([1,+,2,*,3],pf). pf = [+, 1, [*, 2, 3]]

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