Ryan Dickie wrote:
I've only written trivial applications and functions in haskell. But the title of this thread got me thinking.
In an imperative language you have clear steps, states, variables to watch, etc. What techniques/strategies might one use for a functional language?
Well, breakpoints and traces exist, and they're useful, as Stefan showed. However in the presence of a decent repl (ghci) and a useful type system, I most often find myself debugging by trying out my functions in the repl. If your problem is nicely broken down, you can test the smallest functions first, see if they are behaving as expected, and then work up. The 'next step' is to move from testing by hand in ghci to writing quickcheck properties / smallcheck / unit tests for the functions. You'll find the need for imperative-style debugging techniques surprisingly infrequent. Jules