I find that for certain tasks I am incredibly productive with Haskell.
The reason is because of the succinct syntax and the ease of testing.
This is what the function declaration syntax is like:
foo a = a + 5
That's is simplest way I can think of defining a function.
If I write the inverse
inverseFoo a = a - 5
I can check that it is an inverse for any random input by writing
prop_IsInverse :: Double -> Bool
prop_IsInverse a = a == (inverseFoo $ foo a)
And calling from the command line
jonny@ubuntu: runhaskell quickCheck +names fooFileName.hs
Which will check that all the properties in my file are held, by randomly testing inputs a hundred times of so.
I don't think Haskell is the perfect language for everything, but when it comes to writing little functions and testing, I haven't seen anything better. If your programming has a mathematical component this is very important.
