lisp-koans/unused-test-ideas.lsp

;;   Copyright 2013 Google Inc.
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;;   Licensed under the Apache License, Version 2.0 (the "License");
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; todo: add the nconc example somewhere and take care of the warning.

'(define-test test-nconc
    "nconc like append attaches one list to the end of the other, but
     it does so in a more efficient, but potentially destructive way.
     Lisp lists are nil terminated.  A symbol refers to the beginning of
     a list, and then progresses to find the end.  'nconc' simply takes
     the nil pointer at the end of the first list, and points it at the
     beginning of the next list."
  (assert-equal '(:a :b :c) (nconc '(:a :b) '(:c))) ;k

  (let ((abc '(:a :b :c))
        (xyz '(:x :y :z))
        (abcxyz nil))
    (setf abcxyz (nconc abc xyz))
    (assert-equal '(:a :b :c :x :y :z) abcxyz)
    (assert-equal '(:a :b :c :x :y :z) abc)
    (assert-equal '(:x :y :z) xyz)))