Hello Michael How about - Type Driven Development? Personally, I like to work out the type a function should have, then set about writing it. So I usually start from the type signature and stub out the right-hand side of the definition (i.e. all the function after the equals sign) with 'undefined'. Working like this is far from universal in functional programming - it would be unnatural in Scheme for instance, though some people using PLT Scheme appear to start development by writing contract signatures. It certainly isn't universal in Haskell either - some people like to write their functions then fill in the type signature afterwards (if you do it this way, providing your function compiles, you can query its 'most general' type at GHCi's prompt). ML used to have the proviso that type checking was always guaranteed to terminate so type signatures were discretionary, I'm not sure if this is still the case with O'Caml as it now seems to have quite an extended type system. Certain bits of Haskell need explicit type signatures - one example is polymorphic recursion. I suspect very few people programming in Haskell use tests as the primary 'driver' of their program designs (my interpretation of Test Driven Developments slogans is that testing very much drives design). I'd guess quite a number of people develop 'in tandem' with QuickCheck (rather than strictly 'first' with QuickCheck) - for example, there is a blog post on the XMonad window system covering how the authors worked in this way. http://cgi.cse.unsw.edu.au/~dons/blog/2007/05/01 Best wishes Stephen
I'm a fan of Haskell but I can't say that I know the culture yet.
PS. I'd like to think Haskell has at least 'cultures' (or schools, factions?) rather than a unified culture or way. If you like developing test-first, why change if it works.