44 lines
1.9 KiB
Common Lisp
44 lines
1.9 KiB
Common Lisp
;;; Copyright 2013 Google Inc.
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;;;
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;;; Licensed under the Apache License, Version 2.0 (the "License");
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;;; you may not use this file except in compliance with the License.
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;;; You may obtain a copy of the License at
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;;;
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;;; http://www.apache.org/licenses/LICENSE-2.0
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;;;
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;;; Unless required by applicable law or agreed to in writing, software
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;;; distributed under the License is distributed on an "AS IS" BASIS,
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;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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;;; See the License for the specific language governing permissions and
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;;; limitations under the License.
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;;; Lists in lisp are forms beginning and ending with rounded parentheses.
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;;; Atoms are symbols, numbers, or other forms usually separated by whitespace
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;;; or parentheses.
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(define-test list-or-atom
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;; The function LISTP will return true if the input is a list.
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;; The function ATOM will return true if the input is an atom.
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(true-or-false? ____ (listp '(1 2 3)))
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(true-or-false? ____ (atom '(1 2 3)))
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(true-or-false? ____ (listp '("heres" "some" "strings")))
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(true-or-false? ____ (atom '("heres" "some" "strings")))
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(true-or-false? ____ (listp "a string"))
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(true-or-false? ____ (atom "a string"))
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(true-or-false? ____ (listp 2))
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(true-or-false? ____ (atom 2))
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(true-or-false? ____ (listp '(("first" "list") ("second" "list"))))
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(true-or-false? ____ (atom '(("first" "list") ("second" "list")))))
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(define-test the-duality-of-nil
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;; The empty list, NIL, is unique in that it is both a list and an atom.
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(true-or-false? ____ (listp nil))
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(true-or-false? ____ (atom nil)))
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(define-test keywords
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;; Symbols like :HELLO or :LIKE-THIS are keywords. They are treated
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;; differently in Lisp: they are constants that always evaluate to themselves.
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(true-or-false? ____ (equal :this-is-a-keyword :this-is-a-keyword))
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(true-or-false? ____ (equal :this-is-a-keyword ':this-is-a-keyword))
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(true-or-false? ____ (equal :this-is-a-keyword :this-is-also-a-keyword)))
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