Re: function to split a string into a list of characters

Eric Smith wrote:

; (rm1 "abc" 0) ==> "bc"      (rm1 "tea" 1) ==> "ta"
(defun rm1 (seq which)
  (remove-if #'true seq :start which :end (1+ which)))
 
; (consword #\a "bc") ==> "abc"
(defun consword (char word)
  (concatenate 'string (string char) word))
 
; (anagrams "ah") ==> ("ah" "ha")
(defun anagrams (word)
  (if (= (length word) 1) (list word)
    (loop as x across word
          as i upfrom 0
          as subword = (rm1 word i)
          nconc (loop as y in (anagrams subword)
                      collect (consword x y)))))

Gauche Scheme

(use util.combinations) ;; permutations

(define (anagrams word)
  ;; Clojure-style threading or pipelining.
  (->>  word  string->list  permutations  (map list->string)))

(anagrams "try")
  ===>
("try" "tyr" "rty" "ryt" "ytr" "yrt")

Given:

(define-syntax ->>
  (syntax-rules ()
    [(_ x)  x]
    [(_ x (y ...) z ...)
     (->> (y ... x) z ...)]
    [(_ x y z ...)
     (->> (y x) z ...)]))