git @ Cat's Eye Technologies Robin / master stdlib / xor.robin
master

Tree @master (Download .tar.gz)

xor.robin @master — raw · history · blame 

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
;'<<SPEC'

<!--
Copyright (c) 2012-2024, Chris Pressey, Cat's Eye Technologies.
This file is distributed under a 2-clause BSD license.  See LICENSES/ dir.
SPDX-License-Identifier: LicenseRef-BSD-2-Clause-X-Robin
-->

### `xor` ###

    -> Tests for functionality "Evaluate Robin Expression (with Boolean)"

`xor` evaluates both of its arguments to boolean, then evaluates to
the "exclusive-or" of those booleans.

    | (xor #t #t)
    = #f

    | (xor #t #f)
    = #t

    | (xor #f #t)
    = #t

    | (xor #f #f)
    = #f

`xor` expects exactly two arguments.

    | (xor #f)
    ? abort (illegal-arguments

    | (xor #t #f #f)
    ? abort (illegal-arguments

`xor` expects both of its arguments to be booleans.

    | (xor 100 #t)
    ? abort (expected-boolean 100)

    | (xor #t 99)
    ? abort (expected-boolean 99)

This test demonstrates that these functions really do evaluate their
arguments.

    | (and (or (xor (and #t (not (not #t))) #f) #f) #t)
    = #t

'<<SPEC'

(define xor (fun (a b)
  (or (and a (not b)) (and (not a) b))))