On Wed, Nov 10, 2010 at 10:40 AM, namekuseijin <namekusei...@gmail.com> wrote: > On Wed, Nov 10, 2010 at 12:13 AM, John Clements > <cleme...@brinckerhoff.org> wrote: >> ;; NOW I'M A STUDENT: >> >> ;; only-long-strings : (listof string) -> (listof string) >> ;; return a list containing the strings longer than 2 chars >> (define/noloop (only-long-strings l) >> (cond [(empty? l) empty] >> [else (cond [(< 2 (string-length (first l))) >> (cons (first l) >> (only-long-strings (rest l)))] >> [else (only-long-strings l)])])) > > gosh, students do suck. I guess you teach them to use cond because > it's a generalized if. But then they proceed to use it just like if: > always two conditions per (verbose) cond! :p
I disagree - the outer `cond' has 2 clauses because it it processing a data definition - (listof string) - which has 2 clauses. The second `cond' clause, which processes conses, has a conditional as well, but there's certainly nothing wrong with having the structure of your program match the structure of your data, especially not for HtDP programs. -- sam th sa...@ccs.neu.edu _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
