## digitalmars.D.bugs - [Issue 8224] New: Problem with std.functional.unaryFun

```http://d.puremagic.com/issues/show_bug.cgi?id=8224

Summary: Problem with std.functional.unaryFun
Product: D
Version: D2
Platform: x86
OS/Version: Windows
Status: NEW
Severity: normal
Priority: P2
Component: Phobos
AssignedTo: nobody puremagic.com
ReportedBy: bearophile_hugs eml.cc

--- Comment #0 from bearophile_hugs eml.cc 2012-06-11 13:33:22 PDT ---
import std.stdio: writefln;
import std.math: sin, asin, cos, acos, cbrt, pow;
import std.functional: compose;
import std.typetuple: TypeTuple;
void main() {
const sin  = (in real x) => sin(x);
const asin = (in real x) => asin(x);
const cos  = (in real x) => cos(x);
const acos = (in real x) => acos(x);
const cube = (in real x) => x ^^ 3;
const cbrt = (in real x) => cbrt(x);
alias TypeTuple!(sin,  cos,  cube) dir;
alias TypeTuple!(asin, acos, cbrt) inv;
foreach (i, f; dir)
writefln("%6.3f", compose!(f, inv[i])(0.5));
}

Output, dmd 2.060alpha:
0.500
0.866
0.713

Expected output similar to:
0.500
0.500
0.500

Including the source code of std.functional.compose and simplifying it, it
shows the problem still:

import std.functional: unaryFun;
template compose2(fun...) {
alias unaryFun!(fun) fun0;
alias unaryFun!(fun) fun1;
auto compose2(T)(T a) {
return fun0(fun1(a));
}
}
void main() {
import std.stdio, std.math, std.typetuple;
const sin  = (in real x) => sin(x);
const asin = (in real x) => asin(x);
const cos  = (in real x) => cos(x);
const acos = (in real x) => acos(x);
const cube = (in real x) => x ^^ 3;
const cbrt = (in real x) => cbrt(x);
alias TypeTuple!(sin,  cos,  cube) dir;
alias TypeTuple!(asin, acos, cbrt) inv;
foreach (i, f; dir)
writefln("%6.3f", compose2!(f, inv[i])(0.5));
}

Output, dmd 2.060alpha:
0.500
0.866
0.713

Removing the unaryFun!() the results become correct:

import std.functional: unaryFun;
template compose2(fun...) {
alias fun fun0;
alias fun fun1;
auto compose2(T)(T a) {
return fun0(fun1(a));
}
}
void main() {
import std.stdio, std.math, std.typetuple;
const sin  = (in real x) => sin(x);
const asin = (in real x) => asin(x);
const cos  = (in real x) => cos(x);
const acos = (in real x) => acos(x);
const cube = (in real x) => x ^^ 3;
const cbrt = (in real x) => cbrt(x);
alias TypeTuple!(sin,  cos,  cube) dir;
alias TypeTuple!(asin, acos, cbrt) inv;
foreach (i, f; dir)
writefln("%6.3f", compose2!(f, inv[i])(0.5));
}

Output, dmd 2.060alpha:
0.500
0.500
0.500

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Jun 11 2012