1const expect = @import("std").testing.expect;
 2
 3test "optional type" {
 4    // Declare an optional and coerce from null:
 5    var foo: ?i32 = null;
 6
 7    // Coerce from child type of an optional
 8    foo = 1234;
 9
10    // Use compile-time reflection to access the child type of the optional:
11    try comptime expect(@typeInfo(@TypeOf(foo)).optional.child == i32);
12}
13
14// test