I have used std.algorithm.canFind with different tuple types by mistake, and the compiler has not complained. So to show it I have written some reduced code that uses just numbers:


import std.algorithm: canFind;
void main() {
    int[] arr1 = [1, 2];
    double x1 = 2.0;
    assert(arr1.canFind(x1));
    double[] arr2 = [1.0, 2.0];
    int x2 = 2;
    assert(arr2.canFind(x2));
}


Are both of those canFind calls acceptable?

Bye,
bearophile

On Thursday, November 29, 2012 15:28:56 bearophile wrote:
> I have used std.algorithm.canFind with different tuple types by mistake, and the compiler has not complained. So to show it I have written some reduced code that uses just numbers:
> 
> 
> import std.algorithm: canFind;
> void main() {
> int[] arr1 = [1, 2];
> double x1 = 2.0;
> assert(arr1.canFind(x1));
> double[] arr2 = [1.0, 2.0];
> int x2 = 2;
> assert(arr2.canFind(x2));
> }
> 
> 
> Are both of those canFind calls acceptable?

Why wouldn't they be? You can compare int and double, and that's what find and canFind care about.

- Jonathan M Davis

Jonathan M Davis:

> Why wouldn't they be? You can compare int and double, and that's what find and canFind care about.

Right, it's a matter of equality operator.

In my code I was performing canFind on an array of tuples. So I didn't realize that the following code (where both tuple field type and field name are different) is accepted in D (probably I am getting used to the higher type strictness of functional languages):


import std.typecons: Tuple;
alias T1 = Tuple!(int, "x");
alias T2 = Tuple!(double, "y");
void main(string[] args) {
    assert(T1(1) == T2(1));
}


Bye,
bearophile