This is the TXR Lisp interactive listener of TXR 233.
  Quit with :quit or Ctrl-D on empty line. Ctrl-X ? for cheatsheet.
  1> (countq #\h "fhqwhgads")
  2
  2> [[callf equal identity reverse] "palindrome"]
  nil
  3> [[callf equal identity reverse] "racecar"]
  t
  4> [(opip (mappend [iff (op > (countq @1 @@1) 1) list] @1) uniq) "applause"]
  "ap"
  5> [(opip (mappend [iff (op > (countq @1 @@1) 1) list] @1) uniq) "foo"]
  "o"
  6> [(opip (mappend [iff (op > (countq @1 @@1) 1) list] @1) uniq) "baz"]
  ""
  7> [[mapf equal sort sort] "teapot" "toptea"]
  t
  8> [[mapf equal identity sort] "apple" "elap"]
  nil
  9> [(op mappend [iff (op eql (countq @1 @@1) 1) list] @1) "somewhat heterogeneous"]
  "mwa rgnu"
  10> [(do and (= (len @1) (len @2)) (search-str `@2@2` @1)) "foobar" "barfoo"]
  3
  11> [(do and (= (len @1) (len @2)) (search-str `@2@2` @1)) "fboaro" "foobar"]
  nil
  12> [sort '#"books apple peanut aardvark melon pie" : len]
  ("pie" "books" "apple" "melon" "peanut" "aardvark")

Yawn ...

  13> (perm "xyz")  ;; non-recursive, lazy, written in C.
  ("xyz" "xzy" "yxz" "yzx" "zxy" "zyx")