Those are two separate facts:<p>1. Haskell may be a very good language to use for this particular problem set, probably better than the languages currently used for it.<p>2. People in general don&#x27;t use Haskell and will likely resist attempts to change that.<p>So <i>in theory</i> Haskell is a good choice (because reasons) but <i>in practise</i> it isn&#x27;t (because developers in general won&#x27;t be a able to understand&#x2F;maintain the resulting codebase) so he is using something else instead that avoids this problem (but he may think is a less than ideal choice in other ways).