First Month of Haskell

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I’ve been excpetionally fortunate in the past month to accomplish a long held goal of mine. As of the 13th of April I’ve been employed full time as a functional programmer. In particular I’ve taken the deepest of dives into Haskell. I thought it might be interesting, at least for me, to write up my thoughts after completing a month of Haskell.

First the depth of the dive has been overwhelming and the learning curve more equivalent to a vertical rock climb. But the entire time, no matter the exhaustion and believe me there was a lot of that, has been extrodinary. When I take a moment to reflect, I’ve had a smile on my face.

First thing, the degree to which types are ingrained in Haskell. That might seem surprising in itself, Haskell is afterall a strongly typed langauge and it was surprising to me too. I’ve used Erlang, with dialyzer, and OCaml a great deal before starting, and both these languages have reasonable type systems. Ocaml is even described as strongly typed. So what am I getting at?

Everything in Haskell feels typed to the nth degree. Every possible abstraction is pulled out into a common place, either Applicatives, Monads, Bimaps or Monad Transformers. Which is great that you can abstract like that. Using any Haskell library will require you to know about some of these things.

Coming from a background where I’d done Lisp, Erlang and OCaml, and some Haskell I thought I was totally prepared to start working in Haskell full time.

Learning Haskell the language is a good first step, but knowing the syntax and being comfortable reading code is one thing. What really surprised me was that knowing Haskell isn’t sufficient, you need to learn the set of typical Haskell libraries before you can really start making progress and feel at home in Haskell. Of course I’d used things like Monads in OCaml and read

No equivalent to Monad, Monad transformers, lenses, applicative, traversable library eco-system in OCaml. I naievely wonder why this hasn’t been built before and whether it’s even a good idea. The parallels to Scala and scalaz are all too apparent to me. Scala is a mixed OO/FP langauge in a similar way to OCaml. It also doesn’t enforce the same level of strictness with respect to side effects that Haskell does. So in both langauges if you want you can create a mess of side effectey code if you;re not careful. Also both langauges allow mutation, again another side effect, without tracking this via the type system.

I want to thank Mark Hibberd and Charles O’Farrell for being such great mentors over the last month, may they never grow tired of my endless questions.

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