| 1 | ---
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| 2 | title: Builtin Functions (Oils Reference)
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| 3 | all_docs_url: ..
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| 4 | body_css_class: width40
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| 5 | default_highlighter: oils-sh
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| 6 | preserve_anchor_case: yes
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| 7 | ---
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| 8 |
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| 9 | <div class="doc-ref-header">
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| 10 |
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| 11 | [Oils Reference](index.html) —
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| 12 | Chapter **Builtin Functions**
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| 13 |
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| 14 | </div>
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| 15 |
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| 16 | This chapter describes builtin functions (as opposed to [builtin
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| 17 | commands](chap-builtin-cmd.html).)
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| 18 |
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| 19 | <span class="in-progress">(in progress)</span>
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| 20 |
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| 21 | <div id="dense-toc">
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| 22 | </div>
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| 23 |
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| 24 | ## Values
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| 25 |
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| 26 | ### len()
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| 27 |
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| 28 | Returns the
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| 29 |
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| 30 | - number of entries in a `List`
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| 31 | - number of pairs in a `Dict`
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| 32 | - number of bytes in a `Str`
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| 33 | - TODO: `countRunes()` can return the number of UTF-8 encoded code points.
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| 34 |
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| 35 | ### func/type()
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| 36 |
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| 37 | Given an arbitrary value, returns a string representing the value's runtime
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| 38 | type.
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| 39 |
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| 40 | For example:
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| 41 |
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| 42 | var d = {'foo': 'bar'}
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| 43 | var n = 1337
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| 44 |
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| 45 | $ = type(d)
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| 46 | (Str) 'Dict'
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| 47 |
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| 48 | $ = type(n)
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| 49 | (Str) 'Int'
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| 50 |
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| 51 | Similar names: [type][]
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| 52 |
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| 53 | [type]: chap-index.html#type
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| 54 |
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| 55 |
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| 56 | ## Conversions
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| 57 |
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| 58 | ### bool()
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| 59 |
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| 60 | Returns the truth value of its argument. Similar to `bool()` in python, it
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| 61 | returns `false` for:
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| 62 |
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| 63 | - `false`, `0`, `0.0`, `''`, `{}`, `[]`, and `null`.
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| 64 |
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| 65 | Returns `true` for all other values.
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| 66 |
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| 67 | ### int()
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| 68 |
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| 69 | Given a float, returns the largest integer that is less than its argument (i.e. `floor()`).
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| 70 |
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| 71 | $ = int(1.99)
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| 72 | (Int) 1
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| 73 |
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| 74 | Given a string, `Int()` will attempt to convert the string to a base-10
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| 75 | integer. The base can be overriden by calling with a second argument.
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| 76 |
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| 77 | $ = int('10')
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| 78 | (Int) 10
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| 79 |
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| 80 | $ = int('10', 2)
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| 81 | (Int) 2
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| 82 |
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| 83 | ysh$ = Int('foo')
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| 84 | # fails with an expression error
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| 85 |
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| 86 | ### float()
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| 87 |
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| 88 | Given an integer, returns the corressponding flaoting point representation.
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| 89 |
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| 90 | $ = float(1)
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| 91 | (Float) 1.0
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| 92 |
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| 93 | Given a string, `Float()` will attempt to convert the string to float.
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| 94 |
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| 95 | $ = float('1.23')
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| 96 | (Float) 1.23
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| 97 |
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| 98 | ysh$ = float('bar')
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| 99 | # fails with an expression error
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| 100 |
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| 101 | ### str()
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| 102 |
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| 103 | Converts a `Float` or `Int` to a string.
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| 104 |
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| 105 | ### list()
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| 106 |
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| 107 | Given a list, returns a shallow copy of the original.
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| 108 |
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| 109 | Given an iterable value (e.g. a range or dictionary), returns a list containing
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| 110 | one element for each item in the original collection.
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| 111 |
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| 112 | $ = list({'a': 1, 'b': 2})
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| 113 | (List) ['a', 'b']
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| 114 |
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| 115 | $ = list(1:5)
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| 116 | (List) [1, 2, 3, 4, 5]
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| 117 |
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| 118 | ### dict()
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| 119 |
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| 120 | Given a dictionary, returns a shallow copy of the original.
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| 121 |
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| 122 | ### runes()
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| 123 |
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| 124 | TODO
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| 125 |
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| 126 | Given a string, decodes UTF-8 into a List of integer "runes" (aka code points).
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| 127 |
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| 128 | Each rune is in the range `U+0` to `U+110000`, and **excludes** the surrogate
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| 129 | range.
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| 130 |
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| 131 | runes(s, start=-1, end=-1)
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| 132 |
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| 133 | TODO: How do we signal errors?
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| 134 |
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| 135 | (`runes()` can be used to implement implemented Python's `ord()`.)
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| 136 |
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| 137 | ### encodeRunes()
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| 138 |
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| 139 | TODO
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| 140 |
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| 141 | Given a List of integer "runes" (aka code points), return a string.
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| 142 |
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| 143 | (`encodeRunes()` can be used to implement implemented Python's `chr()`.)
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| 144 |
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| 145 | ### bytes()
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| 146 |
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| 147 | TODO
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| 148 |
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| 149 | Given a string, return a List of integer byte values.
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| 150 |
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| 151 | Each byte is in the range 0 to 255.
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| 152 |
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| 153 | ### encodeBytes()
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| 154 |
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| 155 | TODO
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| 156 |
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| 157 | Given a List of integer byte values, return a string.
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| 158 |
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| 159 | ## Str
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| 160 |
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| 161 | ### strcmp()
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| 162 |
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| 163 | TODO
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| 164 |
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| 165 | ### split()
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| 166 |
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| 167 | TODO
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| 168 |
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| 169 | If no argument is passed, splits by whitespace
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| 170 |
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| 171 | <!-- respecting Unicode space? -->
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| 172 |
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| 173 | If a delimiter Str with a single byte is given, splits by that byte.
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| 174 |
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| 175 | Modes:
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| 176 |
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| 177 | - Python-like algorithm
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| 178 | - Is awk any different?
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| 179 | - Split by eggex
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| 180 |
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| 181 | ### shSplit()
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| 182 |
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| 183 | Split a string into a List of strings, using the shell algorithm that respects
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| 184 | `$IFS`.
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| 185 |
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| 186 | Prefer `split()` to `shSplit()`.
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| 187 |
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| 188 |
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| 189 | ## List
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| 190 |
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| 191 | ### join()
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| 192 |
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| 193 | Given a List, stringify its items, and join them by a separator. The default
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| 194 | separator is the empty string.
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| 195 |
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| 196 | var x = ['a', 'b', 'c']
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| 197 |
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| 198 | $ echo $[join(x)]
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| 199 | abc
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| 200 |
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| 201 | $ echo $[join(x, ' ')] # optional separator
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| 202 | a b c
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| 203 |
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| 204 |
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| 205 | It's also often called with the `=>` chaining operator:
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| 206 |
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| 207 | var items = [1, 2, 3]
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| 208 |
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| 209 | json write (items => join()) # => "123"
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| 210 | json write (items => join(' ')) # => "1 2 3"
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| 211 | json write (items => join(', ')) # => "1, 2, 3"
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| 212 |
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| 213 | ## Float
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| 214 |
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| 215 | ### floatsEqual()
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| 216 |
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| 217 | Check if two floating point numbers are equal.
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| 218 |
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| 219 | = floatsEqual(42.0, 42.0)
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| 220 | (Bool) true
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| 221 |
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| 222 | It's usually better to make an approximate comparison:
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| 223 |
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| 224 | = abs(float1 - float2) < 0.001
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| 225 | (Bool) false
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| 226 |
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| 227 | ## Word
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| 228 |
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| 229 | ### glob()
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| 230 |
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| 231 | See `glob-pat` topic for syntax.
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| 232 |
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| 233 | ### maybe()
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| 234 |
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| 235 | ## Serialize
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| 236 |
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| 237 | ### toJson()
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| 238 |
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| 239 | Convert an object in memory to JSON text:
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| 240 |
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| 241 | $ = toJson({name: "alice"})
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| 242 | (Str) '{"name":"alice"}'
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| 243 |
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| 244 | Add indentation by passing the `space` param:
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| 245 |
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| 246 | $ = toJson([42], space=2)
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| 247 | (Str) "[\n 42\n]"
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| 248 |
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| 249 | Similar to `json write (x)`, except the default value of `space` is 0.
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| 250 |
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| 251 | See [err-json-encode][] for errors.
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| 252 |
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| 253 | [err-json-encode]: chap-errors.html#err-json-encode
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| 254 |
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| 255 | ### fromJson()
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| 256 |
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| 257 | Convert JSON text to an object in memory:
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| 258 |
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| 259 | = fromJson('{"name":"alice"}')
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| 260 | (Dict) {"name": "alice"}
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| 261 |
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| 262 | Similar to `json read <<< '{"name": "alice"}'`.
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| 263 |
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| 264 | See [err-json-decode][] for errors.
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| 265 |
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| 266 | [err-json-decode]: chap-errors.html#err-json-decode
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| 267 |
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| 268 | ### toJson8()
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| 269 |
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| 270 | Like `toJson()`, but it also converts binary data (non-Unicode strings) to
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| 271 | J8-style `b'foo \yff'` strings.
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| 272 |
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| 273 | In contrast, `toJson()` will do a lossy conversion with the Unicode replacement
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| 274 | character.
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| 275 |
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| 276 | See [err-json8-encode][] for errors.
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| 277 |
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| 278 | [err-json8-encode]: chap-errors.html#err-json8-encode
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| 279 |
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| 280 | ### fromJson8()
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| 281 |
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| 282 | Like `fromJson()`, but it also accepts binary data denoted by J8-style `b'foo
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| 283 | \yff'` strings.
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| 284 |
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| 285 | See [err-json8-decode][] for errors.
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| 286 |
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| 287 | [err-json8-decode]: chap-errors.html#err-json8-decode
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| 288 |
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| 289 | ## Pattern
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| 290 |
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| 291 | ### `_group()`
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| 292 |
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| 293 | Like `Match => group()`, but accesses the global match created by `~`:
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| 294 |
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| 295 | if ('foo42' ~ / d+ /) {
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| 296 | echo $[_group(0)] # => 42
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| 297 | }
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| 298 |
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| 299 | ### `_start()`
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| 300 |
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| 301 | Like `Match => start()`, but accesses the global match created by `~`:
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| 302 |
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| 303 | if ('foo42' ~ / d+ /) {
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| 304 | echo $[_start(0)] # => 3
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| 305 | }
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| 306 |
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| 307 | ### `_end()`
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| 308 |
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| 309 | Like `Match => end()`, but accesses the global match created by `~`:
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| 310 |
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| 311 | if ('foo42' ~ / d+ /) {
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| 312 | echo $[_end(0)] # => 5
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| 313 | }
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| 314 |
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| 315 | ## Introspection
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| 316 |
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| 317 | ### `shvarGet()`
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| 318 |
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| 319 | Given a variable name, return its value. It uses the "dynamic scope" rule,
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| 320 | which looks up the stack for a variable.
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| 321 |
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| 322 | It's meant to be used with `shvar`:
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| 323 |
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| 324 | proc proc1 {
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| 325 | shvar PATH=/tmp { # temporarily set PATH in this stack frame
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| 326 | my-proc
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| 327 | }
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| 328 |
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| 329 | proc2
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| 330 | }
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| 331 |
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| 332 | proc proc2 {
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| 333 | proc3
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| 334 | }
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| 335 |
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| 336 | proc proc3 {
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| 337 | var path = shvarGet('PATH') # Look up the stack (dynamic scoping)
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| 338 | echo $path # => /tmp
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| 339 | }
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| 340 |
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| 341 | proc1
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| 342 |
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| 343 | Note that `shvar` is usually for string variables, and is analogous to `shopt`
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| 344 | for "booleans".
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| 345 |
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| 346 | If the variable isn't defined, `shvarGet()` returns `null`. So there's no way
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| 347 | to distinguish an undefined variable from one that's `null`.
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| 348 |
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| 349 | ### `getVar()`
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| 350 |
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| 351 | Given a variable name, return its value.
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| 352 |
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| 353 | $ var x = 42
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| 354 | $ echo $[getVar('x')]
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| 355 | 42
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| 356 |
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| 357 | The variable may be local or global. (Compare with `shvarGet()`.) the "dynamic
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| 358 | scope" rule.)
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| 359 |
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| 360 | If the variable isn't defined, `getVar()` returns `null`. So there's no way to
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| 361 | distinguish an undefined variable from one that's `null`.
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| 362 |
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| 363 | ### `evalExpr()`
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| 364 |
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| 365 | Given a an expression quotation, evaluate it and return its value:
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| 366 |
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| 367 | $ var expr = ^[1 + 2]
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| 368 |
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| 369 | $ = evalExpr(expr)
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| 370 | 3
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| 371 |
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| 372 | ## Hay Config
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| 373 |
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| 374 | ### parseHay()
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| 375 |
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| 376 | ### evalHay()
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| 377 |
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| 378 |
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| 379 | ## Hashing
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| 380 |
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| 381 | ### sha1dc()
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| 382 |
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| 383 | Git's algorithm.
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| 384 |
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| 385 | ### sha256()
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| 386 |
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| 387 |
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| 388 | <!--
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| 389 |
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| 390 | ### Better Syntax
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| 391 |
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| 392 | These functions give better syntax to existing shell constructs.
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| 393 |
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| 394 | - `shQuote()` for `printf %q` and `${x@Q}`
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| 395 | - `trimLeft()` for `${x#prefix}` and `${x##prefix}`
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| 396 | - `trimRight()` for `${x%suffix}` and `${x%%suffix}`
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| 397 | - `trimLeftGlob()` and `trimRightGlob()` for slow, legacy glob
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| 398 | - `upper()` for `${x^^}`
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| 399 | - `lower()` for `${x,,}`
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| 400 | - `strftime()`: hidden in `printf`
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| 401 |
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| 402 | -->
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