Daniel Bünzli wrote: > > Le 25 oct. 08 à 14:43, Martin Jambon a écrit : > >> Now I generally tend to use this: >> >> let x = >> List.map ( >> fun z -> >> very_blabla >> ... >> ) my_list >> in > > I think the best solution is to name your anonymous function, as the > guidelines suggest [1].
It says: "Justification: Much clearer, in particular if the name given to the function is meaningful." I think that's true for typical functional code which follows some clear logic or model. In many cases it's not possible to give a meaningful name to such a function and defining it out of the current block can make things needlessly hard to follow. I can think of 4 cases: 1. anonymous function that fits on one line 2. anonymous function that doesn't fit on one line (my original example) 3. named function defined locally using let-in 4. named function defined globally using let I don't use (3) very much since: * it still causes the outermost function definition to be very long and hard to follow like (2), * and it's okay to define a function globally (4) because there is no serious risk of global namespace pollution, thanks to the module system. I think (3) is most useful for defining named functions that depend on a lot of locally-defined values. This creates a closure, which is often acceptable performance-wise, instead of having to make each parameter of the function explicit. In performance-critical code or maybe imperative code in general, it feels good to control when closures are created. In such cases, avoiding local functions helps. Martin -- http://mjambon.com/ _______________________________________________ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
