alt Hacker News> There is this memo video of S. P. Jones that famously says "Haskell is Useless".
I think that is an unfair characterization of the video and the intent of Haskell's co-creator, based on the rest of your comment. Simon Peyton Jones makes a graph with two dimensions, useful/useless and safe/unsafe. The question he gets at is: how can one distinguish between effectful and effect-free computations in a programming language? He proceeds to characterize most useful languages as unsafe, and Haskell as useless but safe. He then spends the majority of the video talking about how useful languages are becoming safer, and at the same time how Haskell must become useful.
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Great video! Thanks for the link.
It is important to clearly understand that Simon uses the word "useless" in the sense of having no side-effects on the external world i.e. if state changes are not reflected in the external world at some point then there is no practical purpose to it and hence "useless".
Functional languages solved this by using the type system at different levels to combine both effectful and effect-free computations cleanly.
I've loved this video for years, primarily because of SPJ's willingness (and excitement, even) to talk about Haskell's shortcomings. I think SPJ and other important people in the Haskell community are keenly aware that Haskell appeals to a specific demographic and that, to survive as more than just a research plaything, that they need to broaden participation.
The famously friendly "Learn You a Haskell" book features its first "helloworld" program deep into the middle of the book, _after_ functors and (if I recall correctly) monads. It takes a very special beginner programmer to push that far through, working in the REPL, before they can write programs that do basic I/O.
I teach functional programming to college sophomores and juniors, and I would love to teach them Haskell. But I have to meet them where they are, and it would be difficult to do in Haskell. This is why we have taught either F#, Scala, or LISP over the years. F# in particular has a lot of the aesthetic qualities of Haskell while allowing impurity or mutability escape hatches without too much trouble. If somebody has truly beginner-friendly Haskell resources, I would love to hear about it-- I'm apparently not smart enough to chart that path myself.