I wouldn't exactly call Haskell "popular". It isn't as obscure as some programming languages, but realistically, it sees comparatively little use in practice.

I wouldn't exactly call Haskell "popular". It isn't as obscure as some programming languages, but realistically, it sees comparatively little use in practice. And Haskell predates Python, Ruby, JavaScript, Java and C#. It has had a very long time to become more widely used, yet we just haven't seen this happen. It's not like people don't know about it; many students, academics and practitioners have been exposed to it for years now, and it does get a fair amount of hype for a language that has experienced limited use in practice. I just don't think it offers enough benefit for the cost involved with learning and using it. If the balance were better, we'd see it being used. But that isn't the case, so it sees minimal usage.