lisp-koans/koans/evaluation.lsp

;;   Copyright 2013 Google Inc.
;;
;;   Licensed under the Apache License, Version 2.0 (the "License");
;;   you may not use this file except in compliance with the License.
;;   You may obtain a copy of the License at
;;
;;       http://www.apache.org/licenses/LICENSE-2.0
;;
;;   Unless required by applicable law or agreed to in writing, software
;;   distributed under the License is distributed on an "AS IS" BASIS,
;;   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;;   See the License for the specific language governing permissions and
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;; based on http://psg.com/~dlamkins/sl/chapter03-02.html

(define-test test-function-name-is-first-argument
    "In most imperative languages, the syntax of a function call has
     the function name succeeded by a list of arguments.  In lisp,
     the function name and arguments are all part of the same list,
     with the function name the first element of that list."

  "in these examples, the function names are +, -, and *"
  (assert-equal ___ (+ 2 3))
  (assert-equal ___ (- 1 3))
  (assert-equal ___ (* 7 4))
  "'>' and '=' are the boolean functions (predicates) 'greater-than' and
   'equal to'"
  (assert-equal ___ (> 100 4))
  (assert-equal ___ (= 3 3))
  "'NUMBERP' is a predicate which returns true if the argument is a number"
  (assert-equal ___ (numberp 5))
  (assert-equal ___ (numberp "five")))


(define-test test-evaluation-order
    "Arguments to functions are evaluated before the function"
  (assert-equal ___ (* (+ 1 2) (- 13 10))))


(define-test test-quoting-behavior
    "Preceding a list with a quote (') will tell lisp not to evalute a list.
     The quote special form suppresses normal evaluation, an instead returns
     the literal list.
     Evaluating the form (+ 1 2) returns the number 3,
     but evaluating the form '(+ 1 2) returns the list (+ 1 2)"
  (assert-equal ____ (+ 1 2))
  (assert-equal ____ '(+ 1 2))
  "'LISTP' is a predicate which returns true if the argument is a list"
  " the '(CONTENTS) form defines a list literal containing CONTENTS"
  (assert-equal ___ (listp '(1 2 3)))
  (assert-equal ___ (listp 100))
  (assert-equal ___ (listp "Word to your moms I came to drop bombs"))
  (assert-equal ___ (listp nil))
  (assert-equal ___ (listp (+ 1 2)))
  (assert-equal ___ (listp '(+ 1 2)))
  "equalp is an equality predicate"
  (assert-equal ___ (equalp 3 (+ 1 2)))
  "the '(xyz ghi) syntax is syntactic sugar for the (QUOTE (xyz ghi)) function."
  (true-or-false? ___ (equalp '(/ 4 0) (quote (/ 4 0)))))