blob: 10891039e86961e4409bdd96423e343c2024d5ef (
plain) (
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
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
<section xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xml:id="sec-functions-library-asserts">
<title>Assert functions</title>
<section xml:id="function-library-lib.asserts.assertMsg">
<title><function>lib.asserts.assertMsg</function></title>
<subtitle><literal>assertMsg :: Bool -> String -> Bool</literal>
</subtitle>
<xi:include href="./locations.xml" xpointer="lib.asserts.assertMsg" />
<para>
Print a trace message if <literal>pred</literal> is false.
</para>
<para>
Intended to be used to augment asserts with helpful error messages.
</para>
<variablelist>
<varlistentry>
<term>
<varname>pred</varname>
</term>
<listitem>
<para>
Condition under which the <varname>msg</varname> should <emphasis>not</emphasis> be printed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>msg</varname>
</term>
<listitem>
<para>
Message to print.
</para>
</listitem>
</varlistentry>
</variablelist>
<example xml:id="function-library-lib.asserts.assertMsg-example-false">
<title>Printing when the predicate is false</title>
<programlisting><![CDATA[
assert lib.asserts.assertMsg ("foo" == "bar") "foo is not bar, silly"
stderr> trace: foo is not bar, silly
stderr> assert failed
]]></programlisting>
</example>
</section>
<section xml:id="function-library-lib.asserts.assertOneOf">
<title><function>lib.asserts.assertOneOf</function></title>
<subtitle><literal>assertOneOf :: String -> String ->
StringList -> Bool</literal>
</subtitle>
<xi:include href="./locations.xml" xpointer="lib.asserts.assertOneOf" />
<para>
Specialized <function>asserts.assertMsg</function> for checking if <varname>val</varname> is one of the elements of <varname>xs</varname>. Useful for checking enums.
</para>
<variablelist>
<varlistentry>
<term>
<varname>name</varname>
</term>
<listitem>
<para>
The name of the variable the user entered <varname>val</varname> into, for inclusion in the error message.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>val</varname>
</term>
<listitem>
<para>
The value of what the user provided, to be compared against the values in <varname>xs</varname>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>xs</varname>
</term>
<listitem>
<para>
The list of valid values.
</para>
</listitem>
</varlistentry>
</variablelist>
<example xml:id="function-library-lib.asserts.assertOneOf-example">
<title>Ensuring a user provided a possible value</title>
<programlisting><![CDATA[
let sslLibrary = "bearssl";
in lib.asserts.assertOneOf "sslLibrary" sslLibrary [ "openssl" "bearssl" ];
=> false
stderr> trace: sslLibrary must be one of "openssl", "libressl", but is: "bearssl"
]]></programlisting>
</example>
</section>
</section>
|