Zachary Turner wrote:
it's generally considered good practice to specify the full type of a function before the definition. Why is this? It almost seems to go against the principles of type inference.
Michael Mossey wrote:
...it seems a shame to disregard this power by declaring all types.
I concur with the reasons given by previous responders for why it's important to specify type signatures for top-level functions. I'll add that this practice is not at all against the principles of type inference, and you still use its full power: o for auxiliary functions defined in let and where clauses o for functions defined at the interactive prompt o for quick scripting Type inference provides a powerful technique for investigating how to use various tools in Haskell: you use the :type command at the interactive command prompt (or in our IRC channels) to find out what type is assigned to an expression. Besides these direct usages, the compiler makes essential use of type inference whenever you write any non-trivial expression. You may have specified the type of the final result, but the compiler needs to know the type of every intermediate result. This requires type inference because of the very general kinds of polymorphism that Haskell allows. -Yitz