2. http://gist.github.com/142939
On Wed, Jul 8, 2009 at 7:19 PM, Jonas Enlund<jonas.enl...@gmail.com> wrote: > 1. Ok, I'll consider that. > > 2. Yes, I'll post a link when I have uploaded the code somewhere. > > 3. It has not yet arrived > > 4. No. I have two sources of inspiration. Pattern matching in PLT > Scheme and this link: > http://groups.csail.mit.edu/mac/users/gjs/6.945/psets/ps05/ps.txt > (which is almost SICP as it is written by Sussman) > > On Wed, Jul 8, 2009 at 7:15 PM, Sean Devlin<francoisdev...@gmail.com> wrote: >> >> 4. Is this example from SICP? >> >> On Jul 8, 12:12 pm, Sean Devlin <francoisdev...@gmail.com> wrote: >>> This seems like a good use for a macro. A couple of thoughts: >>> >>> 1. Use arrays instead of lists >>> In clojure, it is "best practice" to use arrays for data. So, your >>> macro call should look like this. >>> >>> (match [1 2 3] >>> [1 x] (+ x x) >>> [1 x y] (+ x y)) >>> >>> 2. Could you post the source to match maker? That would help my play >>> around in a REPL >>> >>> 3. As for books go, get yourself a copy of "Programming Clojure" by >>> Stuart Holloway >>> >>> Sean >>> >>> On Jul 8, 11:42 am, Jonas <jonas.enl...@gmail.com> wrote: >>> >>> > Hi. >>> >>> > I'm developing a simple pattern matching library for clojure but I am >>> > having >>> > trouble with macros (which I have almost zero experience with). >>> >>> > I have a function `make-matcher` >>> >>> > (make-matcher <pattern>) >>> >>> > which returns a function that can pattern match on data and returns a >>> > map of bindings (or nil in case of a non-match). >>> >>> > ((make-matcher '(list x y z w)) (list 1 2 3 4)) >>> > ; => {x 1 y 2 z 3 w 4} >>> > ((make-matcher '(list x y z x)) (list 1 2 3 4)) >>> > ; => nil >>> > ((make-matcher '(list 1 x 2 _)) (list 1 2 3 4)) >>> > ; => nil >>> > ((make-matcher '(list 1 x 2 _)) (list 1 3 2 9)) >>> > ; => {x 3} >>> >>> > I have been trying to write the following 'match' macro: >>> >>> > (match <data> >>> > <pattern-1> <body-1> >>> > <pattern-2> <body-2>) >>> >>> > The macro should work like this: >>> >>> > (match (list 1 2 3) >>> > (list 1 x) (+ x x) >>> > (list 1 x y) (+ x y)) >>> > ; => 5 >>> >>> > I have the following macros (none of which works correctly): >>> >>> > ; (letmap {a 1 b 2} (+ a b)) >>> > ; =(should) expand to=> >>> > ; (let [a 1 b 2] (+ a b)) >>> > (defmacro letmap [dict & body] >>> > `(let ~(into [] (reduce concat (eval dict))) >>> > (do ~...@body))) >>> >>> > ; (match (list 1 2 3) >>> > ; (list 1 x) (+ x x) >>> > ; (list 1 x y) (+ x y)) >>> > ; =should expand to something like=> >>> > ; (let [dict (<matcher..> (list 1 2 3))] >>> > ; (if dict >>> > ; (letmap dict (+ 1 x)) >>> > ; (match (list 1 2 3) (list 1 x y) (+ x y)))) >>> > (defmacro match [data & clauses] >>> > (when clauses >>> > (let [pattern (first clauses) >>> > body (second clauses) >>> > matcher (make-matcher pattern)] >>> > `(let [dict# (~matcher ~data)] >>> > (if dict# >>> > (letmap dict# ~body) >>> > (match ~data (next (next ~clauses)))))))) >>> >>> > Any help is appreciated. Also pointers to documents and books where I >>> > can >>> > learn more about macros. >>> >>> > Thanks. >> >> >> > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
