| 1 | ---
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| 2 | in_progress: yes
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| 3 | body_css_class: width40 help-body
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| 4 | default_highlighter: oils-sh
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| 5 | preserve_anchor_case: yes
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| 6 | ---
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| 7 |
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| 8 | Builtin Functions
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| 9 | ===
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| 10 |
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| 11 | This chapter in the [Oils Reference](index.html) describes builtin functions.
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| 12 |
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| 13 | (As opposed to [builtin commands](chap-builtin-cmd.html).
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| 14 |
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| 15 | <div id="toc">
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| 16 | </div>
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| 17 |
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| 18 | ## Values
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| 19 |
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| 20 | ### len()
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| 21 |
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| 22 | Returns the
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| 23 |
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| 24 | - number of entries in a `List`
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| 25 | - number of pairs in a `Dict`
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| 26 | - number of bytes in a `Str`
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| 27 | - TODO: `countRunes()` can return the number of UTF-8 encoded code points.
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| 28 |
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| 29 | ### type()
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| 30 |
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| 31 | Given an arbitrary value, returns a string representing the value's runtime type.
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| 32 |
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| 33 | For example:
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| 34 |
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| 35 | var d = {'foo': 'bar'}
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| 36 | var n = 1337
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| 37 |
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| 38 | $ = type(d)
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| 39 | (Str) 'Dict'
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| 40 |
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| 41 | $ = type(n)
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| 42 | (Str) 'Int'
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| 43 |
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| 44 | ### repeat()
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| 45 |
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| 46 | TODO:
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| 47 |
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| 48 | = repeat('a', 3)
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| 49 | (Str) 'aaa'
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| 50 |
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| 51 | = repeat(['a'], 3)
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| 52 | (List) ['a', 'a', 'a']
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| 53 |
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| 54 | Note that list elements are NOT copied. They are repeated by reference, which
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| 55 | means the List can have aliases.
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| 56 |
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| 57 | = repeat([[42]], 3)
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| 58 | (List) [[42], [42], [42]]
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| 59 |
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| 60 | Modeled after these Python expressions:
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| 61 |
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| 62 | >>> 'a' * 3
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| 63 | 'aaa'
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| 64 | >>> ['a'] * 3
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| 65 | ['a', 'a', 'a']
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| 66 |
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| 67 |
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| 68 | ## Conversions
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| 69 |
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| 70 | ### bool()
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| 71 |
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| 72 | Returns the truth value of its argument. Similar to `bool()` in python, it
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| 73 | returns `false` for:
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| 74 |
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| 75 | - `false`, `0`, `0.0`, `''`, `{}`, `[]`, and `null`.
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| 76 |
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| 77 | Returns `true` for all other values.
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| 78 |
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| 79 | ### int()
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| 80 |
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| 81 | Given a float, returns the largest integer that is less than its argument (i.e. `floor()`).
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| 82 |
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| 83 | $ = int(1.99)
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| 84 | (Int) 1
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| 85 |
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| 86 | Given a string, `Int()` will attempt to convert the string to a base-10
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| 87 | integer. The base can be overriden by calling with a second argument.
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| 88 |
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| 89 | $ = int('10')
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| 90 | (Int) 10
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| 91 |
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| 92 | $ = int('10', 2)
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| 93 | (Int) 2
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| 94 |
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| 95 | ysh$ = Int('foo')
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| 96 | # fails with an expression error
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| 97 |
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| 98 | ### float()
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| 99 |
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| 100 | Given an integer, returns the corressponding flaoting point representation.
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| 101 |
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| 102 | $ = float(1)
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| 103 | (Float) 1.0
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| 104 |
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| 105 | Given a string, `Float()` will attempt to convert the string to float.
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| 106 |
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| 107 | $ = float('1.23')
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| 108 | (Float) 1.23
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| 109 |
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| 110 | ysh$ = float('bar')
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| 111 | # fails with an expression error
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| 112 |
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| 113 | ### str()
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| 114 |
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| 115 | Converts a `Float` or `Int` to a string.
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| 116 |
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| 117 | ### list()
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| 118 |
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| 119 | Given a list, returns a shallow copy of the original.
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| 120 |
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| 121 | Given an iterable value (e.g. a range or dictionary), returns a list containing
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| 122 | one element for each item in the original collection.
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| 123 |
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| 124 | $ = list({'a': 1, 'b': 2})
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| 125 | (List) ['a', 'b']
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| 126 |
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| 127 | $ = list(1:5)
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| 128 | (List) [1, 2, 3, 4, 5]
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| 129 |
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| 130 | ### dict()
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| 131 |
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| 132 | Given a dictionary, returns a shallow copy of the original.
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| 133 |
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| 134 | ### chr()
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| 135 |
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| 136 | (not implemented)
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| 137 |
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| 138 | Convert an integer to a Str with the corresponding UTF-8 encoded code point.
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| 139 |
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| 140 | Integers in the surrogate range are an error.
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| 141 |
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| 142 | = chr(97)
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| 143 | (Str) 'a'
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| 144 |
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| 145 | = chr(0x3bc)
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| 146 | (Str) 'μ'
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| 147 |
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| 148 | ### ord()
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| 149 |
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| 150 | (not implemented)
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| 151 |
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| 152 | Convert a single UTF-8 encoded code point to an integer.
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| 153 |
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| 154 | = ord('a')
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| 155 | (Int) 97
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| 156 |
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| 157 | = ord('μ')
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| 158 | (Int) 956 # same as 0x3bc
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| 159 |
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| 160 | <!-- Do we have character literals like #'a' ? Or just use strings. Small
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| 161 | string optimization helps. -->
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| 162 |
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| 163 | ### runes()
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| 164 |
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| 165 | TODO: Explicit iterator over runes.
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| 166 |
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| 167 | ## Str
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| 168 |
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| 169 | ### strcmp()
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| 170 |
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| 171 | TODO
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| 172 |
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| 173 | ### split()
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| 174 |
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| 175 | TODO
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| 176 |
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| 177 | If no argument is passed, splits by whitespace
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| 178 |
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| 179 | <!-- respecting Unicode space? -->
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| 180 |
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| 181 | If a delimiter Str with a single byte is given, splits by that byte.
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| 182 |
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| 183 | Modes:
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| 184 |
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| 185 | - Python-like algorithm
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| 186 | - Is awk any different?
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| 187 | - Split by eggex
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| 188 |
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| 189 | ### shSplit()
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| 190 |
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| 191 | Split a string into a List of strings, using the shell algorithm that respects
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| 192 | `$IFS`.
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| 193 |
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| 194 | Prefer `split()` to `shSplit()`.
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| 195 |
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| 196 |
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| 197 | ## List
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| 198 |
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| 199 | ### join()
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| 200 |
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| 201 | Given a List, stringify its items, and join them by a separator. The default
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| 202 | separator is the empty string.
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| 203 |
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| 204 | var x = ['a', 'b', 'c']
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| 205 |
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| 206 | $ echo $[join(x)]
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| 207 | abc
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| 208 |
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| 209 | $ echo $[join(x, ' ')] # optional separator
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| 210 | a b c
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| 211 |
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| 212 |
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| 213 | It's also often called with the `=>` chaining operator:
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| 214 |
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| 215 | var items = [1, 2, 3]
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| 216 |
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| 217 | json write (items => join()) # => "123"
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| 218 | json write (items => join(' ')) # => "1 2 3"
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| 219 | json write (items => join(', ')) # => "1, 2, 3"
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| 220 |
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| 221 |
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| 222 | ### any()
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| 223 |
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| 224 | Returns true if any value in the list is truthy (`x` is truthy if `Bool(x)`
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| 225 | returns true).
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| 226 |
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| 227 | If the list is empty, return false.
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| 228 |
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| 229 | = any([]) # => false
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| 230 | = any([true, false]) # => true
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| 231 | = any([false, false]) # => false
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| 232 | = any([false, "foo", false]) # => true
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| 233 |
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| 234 | Note, you will need to `source --builtin list.ysh` to use this function.
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| 235 |
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| 236 | ### all()
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| 237 |
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| 238 | Returns true if all values in the list are truthy (`x` is truthy if `Bool(x)`
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| 239 | returns true).
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| 240 |
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| 241 | If the list is empty, return true.
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| 242 |
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| 243 | = any([]) # => true
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| 244 | = any([true, true]) # => true
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| 245 | = any([false, true]) # => false
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| 246 | = any(["foo", true, true]) # => true
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| 247 |
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| 248 | Note, you will need to `source --builtin list.ysh` to use this function.
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| 249 |
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| 250 | ## Word
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| 251 |
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| 252 | ### glob()
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| 253 |
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| 254 | See `glob-pat` topic for syntax.
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| 255 |
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| 256 | ### maybe()
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| 257 |
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| 258 | ## Math
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| 259 |
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| 260 | ### abs()
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| 261 |
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| 262 | Compute the absolute (positive) value of a number (float or int).
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| 263 |
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| 264 | = abs(-1) # => 1
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| 265 | = abs(0) # => 0
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| 266 | = abs(1) # => 1
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| 267 |
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| 268 | Note, you will need to `source --builtin math.ysh` to use this function.
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| 269 |
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| 270 | ### max()
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| 271 |
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| 272 | Compute the maximum of 2 or more values.
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| 273 |
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| 274 | `max` takes two different signatures:
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| 275 |
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| 276 | 1. `max(a, b)` to return the maximum of `a`, `b`
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| 277 | 2. `max(list)` to return the greatest item in the `list`
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| 278 |
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| 279 | For example:
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| 280 |
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| 281 | = max(1, 2) # => 2
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| 282 | = max([1, 2, 3]) # => 3
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| 283 |
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| 284 | Note, you will need to `source --builtin math.ysh` to use this function.
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| 285 |
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| 286 | ### min()
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| 287 |
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| 288 | Compute the minimum of 2 or more values.
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| 289 |
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| 290 | `min` takes two different signatures:
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| 291 |
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| 292 | 1. `min(a, b)` to return the minimum of `a`, `b`
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| 293 | 2. `min(list)` to return the least item in the `list`
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| 294 |
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| 295 | For example:
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| 296 |
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| 297 | = min(2, 3) # => 2
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| 298 | = max([1, 2, 3]) # => 1
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| 299 |
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| 300 | Note, you will need to `source --builtin math.ysh` to use this function.
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| 301 |
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| 302 | ### round()
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| 303 |
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| 304 | ### sum()
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| 305 |
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| 306 | Computes the sum of all elements in the list.
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| 307 |
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| 308 | Returns 0 for an empty list.
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| 309 |
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| 310 | = sum([]) # => 0
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| 311 | = sum([0]) # => 0
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| 312 | = sum([1, 2, 3]) # => 6
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| 313 |
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| 314 | Note, you will need to `source --builtin list.ysh` to use this function.
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| 315 |
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| 316 | ## Serialize
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| 317 |
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| 318 | ### toJson()
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| 319 |
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| 320 | Convert an object in memory to JSON text:
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| 321 |
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| 322 | $ = toJson({name: "alice"})
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| 323 | (Str) '{"name":"alice"}'
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| 324 |
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| 325 | Add indentation by passing the `space` param:
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| 326 |
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| 327 | $ = toJson([42], space=2)
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| 328 | (Str) "[\n 42\n]"
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| 329 |
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| 330 | Similar to `json write (x)`, except the default value of `space` is 0.
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| 331 |
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| 332 | See [json-encode-err](chap-errors.html#json-encode-err) for errors.
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| 333 |
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| 334 | ### fromJson()
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| 335 |
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| 336 | Convert JSON text to an object in memory:
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| 337 |
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| 338 | = fromJson('{"name":"alice"}')
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| 339 | (Dict) {"name": "alice"}
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| 340 |
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| 341 | Similar to `json read <<< '{"name": "alice"}'`.
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| 342 |
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| 343 | See [json-decode-err](chap-errors.html#json-decode-err) for errors.
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| 344 |
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| 345 | ### toJson8()
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| 346 |
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| 347 | Like `toJson()`, but it also converts binary data (non-Unicode strings) to
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| 348 | J8-style `b'foo \yff'` strings.
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| 349 |
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| 350 | In contrast, `toJson()` will do a lossy conversion with the Unicode replacement
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| 351 | character.
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| 352 |
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| 353 | See [json8-encode-err](chap-errors.html#json8-encode-err) for errors.
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| 354 |
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| 355 | ### fromJson8()
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| 356 |
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| 357 | Like `fromJson()`, but it also accepts binary data denoted by J8-style `b'foo
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| 358 | \yff'` strings.
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| 359 |
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| 360 | See [json8-decode-err](chap-errors.html#json8-decode-err) for errors.
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| 361 |
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| 362 | ## Pattern
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| 363 |
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| 364 | ### `_group()`
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| 365 |
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| 366 | Like `Match => group()`, but accesses the global match created by `~`:
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| 367 |
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| 368 | if ('foo42' ~ / d+ /) {
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| 369 | echo $[_group(0)] # => 42
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| 370 | }
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| 371 |
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| 372 | ### `_start()`
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| 373 |
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| 374 | Like `Match => start()`, but accesses the global match created by `~`:
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| 375 |
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| 376 | if ('foo42' ~ / d+ /) {
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| 377 | echo $[_start(0)] # => 3
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| 378 | }
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| 379 |
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| 380 | ### `_end()`
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| 381 |
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| 382 | Like `Match => end()`, but accesses the global match created by `~`:
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| 383 |
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| 384 | if ('foo42' ~ / d+ /) {
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| 385 | echo $[_end(0)] # => 5
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| 386 | }
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| 387 |
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| 388 | ## Introspection
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| 389 |
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| 390 | ### `shvar_get()`
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| 391 |
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| 392 | TODO
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| 393 |
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| 394 | ## Config Gen
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| 395 |
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| 396 | ### Better Syntax
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| 397 |
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| 398 | These functions give better syntax to existing shell constructs.
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| 399 |
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| 400 | - `shquote()` for `printf %q` and `${x@Q}`
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| 401 | - `lstrip()` for `${x#prefix}` and `${x##prefix}`
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| 402 | - `rstrip()` for `${x%suffix}` and `${x%%suffix}`
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| 403 | - `lstripglob()` and `rstripglob()` for slow, legacy glob
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| 404 | - `upper()` for `${x^^}`
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| 405 | - `lower()` for `${x,,}`
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| 406 | - `strftime()`: hidden in `printf`
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| 407 |
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| 408 |
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| 409 | ## Codecs
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| 410 |
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| 411 | TODO
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| 412 |
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| 413 | ## Hashing
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| 414 |
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| 415 | TODO
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| 416 |
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