"Solutions at the time included various attempts to compile Haskell to JavaScript while preserving its semantics (Fay, Haste, GHCJS), but I was interested to see how successful I could be by approaching the problem from the other side - attempting to keep the semantics of JavaScript, while enjoying the syntax and type system of a language like Haskell."
It's a good reason for the author of the language, and for anyone who's interested in designing programming languages. However, I often wonder why people in the industry promote it as a great choice for developers who are looking for a "Haskell for frontend", instead of recommending GHCJS. I do understand why Elm is recommended instead of Haskell for simplicity reasons, but PureScript is neither simpler nor (presumably, if I'm not missing something) conceptually more valuable (i.e. bringing refreshingly new ideas) than GHC Haskell.
Purescript does have algebraic effects and row polymorphism generally, which Haskell does not AFAIK (I don’t do as much Haskell as I would like so I may be wrong.)
Algebraic effects are not part of the language implementation, but there are libraries like fused-effects[1] that implement them. Row polymorphism has been proposed a few years ago [2], but as with any community effort, the timeline and possibility of the actual implementation depends on the amount of attention put into it instead of some other (probably important, too) work.
"Solutions at the time included various attempts to compile Haskell to JavaScript while preserving its semantics (Fay, Haste, GHCJS), but I was interested to see how successful I could be by approaching the problem from the other side - attempting to keep the semantics of JavaScript, while enjoying the syntax and type system of a language like Haskell."
https://leanpub.com/purescript/read#leanpub-auto-about-the-a...