Code improvement for DNA reverse complement?

[Stefan Koch via Digitalmars-d-learn]

On Friday, 19 May 2017 at 07:29:44 UTC, biocyberman wrote:
> I am solving this problem http://rosalind.info/problems/revc/ 
> as an exercise to learn D. This is my solution:
>
> https://dpaste.dzfl.pl/8aa667f962b7
>
> Is there some D tricks I can use to make the 
> `reverseComplement` function more concise and speedy? Any other 
> comments for improvement of the whole solution are also much 
> appreciated.

I think doing a switch or even a if-else chain would be faster 
then using an AA.