Any Symbolic Expression Lib?

General
15

Here is a stub to interface sympy

sympy.pl:

:- module(sympy, [sympy/2]).

:- use_module(library(janus)),
    py_import(sympy, []).

sympy(A, R) :-
    sym(A, S),
    mys(S, R).

:- discontiguous sym/2, mys/2.

sym(A, S) :-
    atom(A),
    !, py_call(sympy:'Symbol'(A), S).

mys(S, A) :-
    py_call(S:is_symbol, @(true)),
    !, py_call(S:name, A).

sym(A, S) :-
    integer(A),
    !, py_call(sympy:'Integer'(A), S).

mys(S, A) :-
    py_call(S:is_integer, @(true)),
    !, py_call(int(S), A).

sym(A + B, S) :-
    !, sym(A, A1),
    sym(B, B1),
    py_call(operator:add(A1, B1), S).

mys(S, A + B) :-
    py_call(sympy:'Add', Add),
    py_call(isinstance(S, Add), @(true)),
    !, py_call(S:args, A0-B0),
    mys(A0, A),
    mys(B0, B).

sym(A * B, S) :-
    !, sym(A, A1),
    sym(B, B1),
    py_call(operator:mul(A1, B1), S).

mys(S, A * B) :-
    py_call(sympy:'Mul', Mul),
    py_call(isinstance(S, Mul), @(true)),
    !, py_call(S:args, A0-B0),
    mys(A0, A),
    mys(B0, B).

Example:

1 ?- [sympy].
true.

2 ?- sympy(x + y + 1 + x + y + -1, S).
S = 2*x+2*y ;

There’s a choice point at the end, unclear why.

Janus: py_call(1 + 2, Sum)