Why dont languages allow overloading of methods by return value?

Question

c, java and many other languages do not pay attention to return values.

int   i = func()
float f = func()
int   func() { return 5 }
float func() { return 1.3         


        

Answer 1

To avoid ambiguity.

a( int )
a( bool )
int b()
bool b()

a( b() ) -- Which b?

Here type inference has a cyclic dependency. Which b depends on which a, but which a depends on which b, so it gets stuck.

Disallowing overloading of return types ensures that type inference is acyclic. The return type can always be determined by the parameter types, but the parameter types cannot be determined by the return type, since they may in turn be determined by the parameter types you are trying to find.