[Polyml] Re: Type Constraints and Overloading

On 1/29/2026 6:18 PM, Duke Normandin wrote:

Taken from Paulson's book: Chap2.4

A) fun square x = x * x;

...

Error- Unable to resolve overloading for *

I understand the above!

B) fun square(x : real) = x * x; I understand: x is declared as a real

C) fun square x = x * x : real; I see this as declaring a function w/o parentheses AND that the r_result_ is a 'real'

I have a problem with this declaration:

D) fun square x : real = x * x; I see this as declaring a function w/o parentheses, AND declaring x to be a 'real' I do NOT see/understand that this syntax indicates that the type of the _result_ is a 'real'

The type of the result is a real by implication of what * does on reals, i.e., it produces a real.

Eliot Moss