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[Caml-list] Frustrated Beginner
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Date: | 2003-12-23 (06:21) |
From: | Michael Vanier <mvanier@c...> |
Subject: | Re: [Caml-list] Frustrated Beginner |
To learn the functional style of programming I strongly recommend Abelson and Sussman's Structure and Interpretation of Computer Programs. Even though it uses scheme, not ocaml, the functional style easily transfers from one language to another. Mike > Cc: caml-list@inria.fr > From: Tyler Eaves <tyler@ml1.net> > Date: Tue, 23 Dec 2003 01:11:08 -0500 > > > On Dec 23, 2003, at 12:34 AM, Matt Gushee wrote: > > > >> So why is O'Caml giving me so much trouble? > > > > Do you have any previous experience with functional programming (FP), > > or > > have you studied FP in school? If not, then you're learning both a new > > syntax and a very different programming paradigm at once, so you should > > expect a steep learning curve. But I think if you stick with it, after > > a > > while it will all start to make sense, and you'll be glad you made the > > effort. > > Not much, a (very) little Lisp. Not really enough to 'get it'. > > > >> I've been trying to pick it up for about a week now, read various > >> online tutorials. > > > > > http://www.merjis.com/richj/computers/ocaml/tutorial/ > This is the one I've gotten the most out of. > > >> My biggest source of problems seems to be the syntax. I'm totally > >> confused as far as ; vs ;; vs nothing, ... > > > > Yes, that is a bit tricky. You've undoubtedly read explanations of the > > semicolons, but sometimes it helps if you get the same information > > again > > in slightly different terms, so let me try: > > > > * A double semicolon ends a "sentence"--that is, it terminates a > > top-level construct such as a function definition--but not nested > > function definitions, because they're not "sentences," they're > > "phrases". > > > > You can omit ;; in most cases, but I would suggest at first using > > it everywhere it is allowed. When you omit the ;; and there is a > > syntax error in your code, the compiler often goes many lines past > > the real trouble spot before it detects an error, so using ;; > > everywhere can narrow down your search. > > > > * The single semicolon is perhaps a bit harder to understand, but I > > think it helps to keep in mind that OCaml is basically a functional > > language, yet it also supports imperative programming. Being > > functional means that there are no statements per se. It's all > > about > > evaluating expressions, and *every* expression returns a value. > > However, there are expressions that are functionally equivalent to > > statements. In order to conform to the functional model, they have > > to return a value, but there is no useful value to return. So they > > return the unit value, '()'. > > Okay, that helps. > > > Basically, whenever you are programming imperatively--when you have > > one of these pseudo-statements that return (), and when it this > > imperative phrase is not the final result of a function, you need > > to > > separate it from the following phrase with a single semicolon. A > > simple example: > > > > match foo with > > | None -> print_endline "Nothing"; "" > > | Some x -> print_endline x; x > > If I understand the match syntax correctly, in this case, x takes the > value of foo? > > This expression returns a string, but before returning, you want to > > print a message. Printing functions, of course, return (). > > > > Hope this helps a bit. Best of luck to you > > It does, quite a bit. Thanks to everyone else too, I've already gotten > something like 11 replies in an hour and a half :) > > ------------------- > To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr > Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ > Beginner's list: http://groups.yahoo.com/group/ocaml_beginners > ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners