Module ddash.algorithm.equal

Tells you if two things are equal

// single elements
assert(!equal(2, 4));

// unary predicate function applied to elements then compared
assert( equal!(a => a % 2 == 0)(2, 4));
assert( equal!q{a % 2 == 0}(2, 4));

// binary predicate used to compare elements
assert(!equal!((a, b) => a == b)(2, 4));
assert( equal!q{a != b}(2, 4));

// compare ranges of ranges of different range types but same value types
import std.algorithm: map, filter;
auto r1 = [1, 2, 3].map!"a";
auto r2 = [1, 2, 3].filter!"true";
assert( equal([r1], [r2]));

assert( equal([1, 2, 3], [1, 2, 3]));
assert( equal([[1], [2], [3]], [[1], [2], [3]]));

static assert(!__traits(compiles, equal!(a => a)(1, "hi")));

struct S {
    int x;
    int y;
}

auto s1 = S(1, 2);
auto s2 = S(2, 2);

assert( equalBy!"y"(s1, s2));
assert(!equalBy!"x"(s1, s2));

auto r1 = [s2, s2];
auto r2 = [s1, s1];

assert( equalBy!"y"(r1, r2));
assert(!equalBy!"x"(r1, r2));