Module ddash.functional.pred

Example

static struct S(alias pred) {
    auto f(int a, int b) {
        static if (isEq!pred) {
            return pred(a, b);
        } else static if (isLt!pred) {
            return !pred(a, b) && !pred(b, a);
        } else {
            import std.functional: binaryFun;
            return binaryFun!pred(a, b);
        }
    }
}

alias A = S!(eq!((a, b) => a == b));
alias B = S!(lt!((a, b) => a < b));

assert( A().f(1, 1));
assert( B().f(1, 1));
assert(!A().f(2, 1));
assert(!B().f(2, 1));

static bool feq(int a, int b) { return a == b; }
static bool flt(int a, int b) { return a < b; }

alias C = S!(eq!feq);
alias D = S!(lt!flt);

assert( C().f(1, 1));
assert( D().f(1, 1));
assert(!C().f(1, 2));
assert(!D().f(1, 2));

assert(S!"a == b"().f(1, 1));