I just made a small change the removes the useless 'start' procedure. (The first change removed the 'final')
Jay On Sat, Oct 9, 2010 at 8:37 AM, Jay McCarthy <jay.mccar...@gmail.com> wrote: > Carl, yours doesn't pass the test suite. > > For example, you return (void) rather than 3. > > I've fixed that, removed the letrec and added else support. > > http://github.com/jeapostrophe/exp/blob/master/cas-cad-e.rkt > > Jay > > On Sat, Oct 9, 2010 at 7:52 AM, Carl Eastlund <c...@ccs.neu.edu> wrote: >> Here's my solution. It is pure (if you ignore the set! nature of >> letrec), has linear expansion, avoids multiple values, and uses a >> single "case" for conditional tests. The only thing it lacks that I >> know of is support for "else". >> >> -------------------------------------------------------------------------------- >> #lang racket >> (require (for-syntax syntax/parse) racket/stxparam) >> >> (define-syntax-parameter break >> (lambda (stx) (raise-syntax-error #f "used outside of cas-cad-e" stx))) >> >> (define-syntax cas-cad-e >> (syntax-parser >> [(_ e:expr [(v ...) body:expr ...+] ...) >> (with-syntax ([(id ...) (generate-temporaries #'((v ...) ...))]) >> (with-syntax ([(f ...) #'(start id ... finish)] >> [(action ...) #'((begin) (begin body ...) ... (begin))] >> [(next ...) #'(id ... finish void)]) >> #'(let/ec escape >> (syntax-parameterize ([break (make-rename-transformer #'escape)]) >> (letrec ([f (lambda () action (next))] ...) >> (case e [(v ...) (id)] ...))))))])) >> >> (define (nursery-rhyme n) >> (cas-cad-e n >> [(1 2) (displayln "buckle my shoe")] >> [(3 4) (displayln "shut the door") (break)] >> [(5 6) (displayln "pick up sticks")] >> [(7 8) (displayln "lay them straight") (break)] >> [(9 10) (displayln "a big fat hen")])) >> >> (for ([i '(1 2 3 4 5 6 7 8 9 10)]) >> (nursery-rhyme i)) >> -------------------------------------------------------------------------------- >> >> Carl Eastlund >> > > > > -- > Jay McCarthy <j...@cs.byu.edu> > Assistant Professor / Brigham Young University > http://teammccarthy.org/jay > > "The glory of God is Intelligence" - D&C 93 > -- Jay McCarthy <j...@cs.byu.edu> Assistant Professor / Brigham Young University http://teammccarthy.org/jay "The glory of God is Intelligence" - D&C 93 _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
