How to apply a function to a container/array ?

[bearophile via Digitalmars-d-learn]

Domingo:

> Ideally I want to use something like this:
> ---------
> import std.stdio;
> import std.string;
> import std.algorithm;
> import std.conv;
>
> void main()
> {
> 	string[] ar = [" dad ", " blue "];
> 	writeln(typeid(ar));
> 	
> 	//ar.each(writeln);
> 	//ar.map!writeln;
> 	//ar.apply!writeln;
> 	
> 	//string[] ar_striped = ar.map!strip;
> 	//string[] ar_striped = ar.apply!strip;
> 	//string[] ar_striped = ar.each!strip;
> 	
> 	//ar_striped.each!writeln;
> 	//ar_striped.apply!writeln;
> 	//ar_striped.map!writeln;
> 	
> 	
> 	alias stringize = map!(to!string);
> 	auto sz = stringize([ 1, 2, 3, 4 ]);
> 	writeln(typeid(sz));
> 	assert(equal(sz, [ "1", "2", "3", "4" ]));
> }
> ---------
>
> But none of then work, any idea of how to that in D ?

D algorithms like "map" don't return an array, but a lazy range. 
Use ".array" if you need an array:

void main() {
     import std.stdio;
     import std.algorithm;
     import std.array;
     import std.string;
     import std.conv;

     immutable ar = [" dad ", " blue "];
     pragma(msg, typeof(ar));
     ar.writeln;
     auto arStriped = ar.map!strip;
     arStriped.writeln;
     pragma(msg, typeof(arStriped));
     immutable arStripedArray = arStriped.array;
     pragma(msg, typeof(arStripedArray));

     alias stringize = map!text;
     auto sz = stringize([ 1, 2, 3, 4 ]);
     assert(sz.equal(["1", "2", "3", "4"]));
}


Usually it's better to use pragma+typeof, typeid is used less 
often, for run time management/use of types.

Bye,
bearophile