how to count number of letters with std.algorithm.count / std.algorithm.reduce / std.algorithm.map ?

[bearophile]

bioinfornatics:

> should be faster, no ?

If your purpose is to write a fast function to do this, then I 
suggest you to not use Phobos stuff in this function, and to not 
use associative arrays in it, and possibly to not use the heap. 
This is not going to give you assured faster code, but it's a 
start. And then I suggest to start benchmarking, so you will be 
able to answer your own question :-)

Bye,
bearophile