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Since I wrote a bittorrent client in both Erlang and Haskell, etorrent and combinatorrent respectively, I decided to put up some bait. This might erupt in a language war and “My language is better than yours”, but I feel I am obligated to write something subjective. Here is to woes of programming in Haskell and Erlang.Neither Haskell, nor Erlang was a first language for me. I have programmed serious programs in C, Standard ML, Ocaml, Python, Java and Perl; tasted the cake of Go, Javascript, Scheme and Ruby; and has written substantial stuff in Coq and Twelf. I love static type systems, a bias that will rear its ugly head and breathe fire.I have written Haskell code seriously since 2005 and Erlang code seriously since 2007. I have programmed functionally since 1997 or so. My toilet reading currently is “Categories for the working mathematician” by Mac Lane. Ten years ago it was “ML for the working programmer” by Paulson.Enough about me.

We had to cover monads eventually, and there are many great monad tutorials out there (see, for example, here: http://www.haskell.org/haskellwiki/Tutorials#Using_monads). In fact, there are web resources concerned solely with organizing the many monad tutorials available in the wild, and developing new monad tutorials seems to be a popular sport in the Haskell community.Today, Ralf Lämmel's lecture goes back to the roots, essentially revisiting Wadler's "The essence of functional programming"—the 1992 paper that discovered monads and popularized their use in functional programming. Ralf Lämmel's lecture and accompanying code distribution show Wadler's seminal insight: those original scenarios and observations still make sense today. Indeed, Simon Marlow (a Haskell/GHC high priest @ MSR Cambridge) recently noted: "it's still the best monad tutorial" (see http://twitter.com/simonmar/status/21397398061).

First, right off the top here: Scala has true blue Java-like null; any reference may be null. Its presence muddies the water quite a bit. But since Beust's article explicitly talks about Haskell he's clearly not talking about that aspect of Scala because Haskell doesn't have null. I'll get back to Scala's null at the end but for now pretend it doesn't exist.Second, just to set the record straight: "Option" has roots in programming languages as far back as ML. Both Haskell's "Maybe" and Scala's "Option" (and F#'s "Option" and others) trace their ancestry to it.

In this interview made by InfoQ’s Sadek Drobi, Don Syme, a Senior Researcher at Microsoft Research, answers questions mostly on F#, but also on functional programming, C# generics, type classes in Haskell, similarities between F# and Scala.