[dllthomas]

In my experience, to borrow seanmcdirmid's terminology below, one can use Haskell as a "program to think" language - and in fact Haskell brings some significant tools to the table that I miss when I'm using Python to feel around a problem, to the point that I often choose Haskell for this. In both languages, writing small pieces of code and examining their shape and their output can be helpful in growing my understanding of the solution space, but I find that Haskell tends to let me ask more complete questions with less complete code.