LInt implemented in Prolog.

lint.pl

exp(E) --> int(E).
exp(E) --> binop(E).

int(I) --> [I], { integer(I) }.

binop(add(A, B)) --> "+", exp(A), exp(B).
binop(sub(A, B)) --> "-", exp(A), exp(B).
binop(mul(A, B)) --> "*", exp(A), exp(B).
binop(div(A, B)) --> "/", exp(A), exp(B).

eval(int(I), I).
eval(add(A, B), Result) :- eval(A, AVal), eval(B, BVal), Result is AVal + BVal.
eval(sub(A, B), Result) :- eval(A, AVal), eval(B, BVal), Result is AVal - BVal.
eval(mul(A, B), Result) :- eval(A, AVal), eval(B, BVal), Result is AVal * BVal.
eval(div(A, B), Result) :- eval(A, AVal), eval(B, BVal), BVal =\= 0, Result is AVal / BVal.

dot feels more logical than semicolons for ending the line🤔