Function tuples

[John Colvin]

On Friday, 14 March 2014 at 17:10:53 UTC, John Colvin wrote:
> On Friday, 14 March 2014 at 16:38:00 UTC, bearophile wrote:
>> This comes from a Rosettacode entry:
>> http://rosettacode.org/wiki/First-class_functions#D
>>
>>
>> import std.stdio, std.math, std.typetuple, std.functional;
>>
>> enum static sin  = (in real x) pure nothrow => std.math.sin(x),
>>            asin = (in real x) pure nothrow => std.math.asin(x),
>>            cos  = (in real x) pure nothrow => std.math.cos(x),
>>            acos = (in real x) pure nothrow => std.math.acos(x),
>>            cube = (in real x) pure nothrow => x ^^ 3,
>>            cbrt = (in real x) /*pure*/ nothrow => 
>> std.math.cbrt(x);
>>
>> void main() {
>>    alias dir = TypeTuple!(sin,  cos,  cube);
>>    alias inv = TypeTuple!(asin, acos, cbrt);
>>    foreach (immutable i, f; dir) {
>>        writefln("%6.3f %6.3f",
>>                 compose!(f, inv[i])(0.5),
>>                 compose!(dir[i], inv[i])(0.5));
>>    }
>> }
>>
>> It prints:
>>
>> 0.500  0.500
>> 0.866  0.500
>> 0.713  0.500
>>
>> Do you know why there's such difference in the results?
>>
>
> It's a bug, and quite a wierd one at that. See the output from 
> this: http://dpaste.dzfl.pl/1962d61bb185

It's calling sin every time instead of cos or cube