I'm an utter noob to Haskell, and FP in gnereal. I would like to create a function taking an argument which is a function (actually an equation taking no args, but dependent on other equations), which prints the name of the function and and it's result. Is there a way of doing this in Haskell? Sounds like a job for macros, or some kind of introspection-type stuff.
You can't do this in Haskell. In Haskell, functions are very lightweight things, and often they are inlined or compiled away in some way leaving no trace at runtime. So there's nothing to reflect on. This is in contrast to a language like Java, where each object has quite a lot of identity and state, and a large heap footprint. If you *really* want it, you can do something similar with either the C preprocessor or (perhaps) profiling and cost-centre stacks. But you probably don't. Instead, you should pass around data items that contain both the function and its name - either just pairs, like f :: (String, a->b) f = ("successor",\x -> x+1) apply :: (String, a->b) -> a -> b apply (_, ff) x = ff x nameOf :: (String, a->b) -> String nameOf (s,_) = x or proper data types, like data NamedFunc a b = NamedFunc String (a->b) f :: NamedFunc Int Int f = NamedFunc "successor" (\x -> x+1) apply :: NamedFunc a b -> a -> b apply (NamedFunc _ ff) x = ff x nameOf :: NamedFunc a b -> String nameOf (NamedFunc s _) = s HTH. --KW 8-)