std.algorithm.reduce on an array of structs
Colin via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Thu Sep 11 06:06:04 PDT 2014
I have this test code:
struct Thing {
uint x;
}
void main(){
uint[] ar1 = [1, 2, 3, 4, 5];
auto min1 = ar1.reduce!((a,b) => a < b);
writefln("%s", min1); // prints 1 as expected
Thing[] ar2 = [Thing(1), Thing(2), Thing(4)];
auto min2 = ar2.reduce!((a,b) => a.x < b.x); // <- Wont
Compile
writefln("%s", min2);
}
The line with "Wont Compile" on it has this error message:
/usr/include/dmd/phobos/std/algorithm.d(770): Error: cannot
implicitly convert expression (__lambda2(result,
front(_param_1))) of type bool to Thing
/usr/include/dmd/phobos/std/algorithm.d(791): Error: template
instance t.main.reduce!((a, b) => a.x < b.x).reduce!(Thing,
Thing[]) error instantiating
t.d(16): instantiated from here: reduce!(Thing[])
Any idea what I'm doing wrong here?
To me, the operation on ar2 should be pretty much identical to
ar1, except for the use of the struct.
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