-- main.mcl --
# $id could theoretically have type func(int) int or func(str) str, but it
# can't be both because it is bound to a variable, which must have a single
# type.
$id = func($x) {$x}
test "test1" {
	int8 => $id(42),
}
test "test2" {
	anotherstr => $id("hello"),
}
-- OUTPUT --
# err: errUnify: unify error with: topLevel(singleton(func(x) { var(x) })): type error: str != int
# err: errUnify: unify error with: topLevel(singleton(func(x) { var(x) })): type error: int != str
