It's probably too late to suggest, but to me it looks more logical to have "=" instead of ":" whith parameter values. For example if, function is declared as
func sampleFunction(sampleParam: Int) {
...
}
the logical call syntax (a I see it) is
sampleFunction(sampleParam = 1)
The reason: anywhere else, colon (:) is used with types, while equal(=) is actually used with values. Why wouldn't call syntax be consistent?