std.functional.compose compilation error

Antonio Corbi via Digitalmars-d-learn digitalmars-d-learn at puremagic.com
Thu Aug 25 07:06:32 PDT 2016


Hello,

Trying to compile this example from Chuck Allison:
-------------------------------------------
import std.stdio;
import std.functional;

void main() {
     auto div3 = (double x) => x/3.0;
     auto sq = (double x) => x*x;
     auto pls1 = (double x) => x+1.0;
     alias compose!(div3,sq,pls1) comp;
     writeln(comp(2.0)); // 3 == (2.0+1.0)^^2 / 3.0
     alias pipe!(div3,sq,pls1) pip;
     writeln(pip(2.0));  // 1.44444 == (2.0/3.0)^^2 + 1.0
}
--------------------------------------------

I get this error (with DMD64 D Compiler v2.071.1 in linux):

compose.d(8): Error: template instance compose!(div3, sq, pls1) 
compose is not a template declaration, it is a module

But the error disappears if I use this import:
    import std.functional:compose,pipe;

Is this a bug or is it the expected behaviour under the recent 
'import' changes?
Thanks!




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