STM is a very nice parallel programming model used intensively in Haskell and Clojure. There's a F# implementation which can be found in FSharpx library. Today I'm going to test performance of both the Haskell and the F# STMs. The test is very simple - read a couple TVars, check their equality, then write them back incremented by 1, repeat a million times. First, the Haskell code: So, it took about 170 ms. OK, now F#: It took about 1,6 seconds which is an order of magnitude slower than the Haskell result.[...]

Let's look at what F# and Haskell can offer us while reimplementing grouping consecutive integers in C# algorithm. F#: Haskell: For my current taste, the Haskell version is more readable due to the awesome separate type annotation and to the lovely Erlang-style pattern matching on function arguments.

It turned out that it's not Haskell who was slow in my previous Fibonacci test. It was my lack of Haskell knowledge. Haskell has two integral types - Int, which has bounds -2147483648..2147483647 and Integer, which is unbounded. Both types implement Integral type class, so out fib function can be defined in terms of this type class: OK, now we can test performance of the function parametrizing it with the two concrete types. Integer first: We get our previous result ~15 seconds which is rather slow. Now t[...]

Okey, it passed about a year I started learn and use F# and it's now time to learn Haskell. As usual, I started from the naive Fibonacci function: The performance in this particular algorithm is not fantastic, it's actually ~4 times slower than F#. It's OK for now.

Jessica Kerr recently wrote on the very interesting topic: what the best way to get rid of exceptions and of the mess they introduce into the program flow.Simply put, she's gently introduced the Either monad in Scala language.Although I find Scala to be a very advanced OO language with reasonably good FP support, I don't think the code Jessica used in her post can force anybody to change the habitual exception handling flow in favor of the Data Flow. This's why: Scala is too verbose.But this is not the cas[...]