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81 lines
1.6 KiB
Text
81 lines
1.6 KiB
Text
= String operations
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== String concatenation
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String concatenation uses the `+` operator.
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[source]
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....
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nix-repl> "Hello, " + "world!"
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"Hello, world!"
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....
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== String interpolation
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You can use the `${_variable_}` syntax to insert the value of a variable within a string.
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[source]
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....
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nix-repl> name = "Wombat"
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nix-repl> "Hi, I'm ${name}."
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"Hi, I'm Wombat."
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....
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[IMPORTANT]
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====
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You cannot mix numbers and strings.
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Earlier we set `a = 7`, so the following expression fails.
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[source]
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....
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nix-repl> "My favourite number is ${a}."
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error:
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… while evaluating a path segment
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at «string»:1:25:
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1| "My favourite number is ${a}."
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| ^
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error: cannot coerce an integer to a string
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....
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Nix does provide functions for converting between types; we'll see these in the
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<<#convert-to-string,next section>>.
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====
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== Useful built-in functions for strings
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Nix provides some built-in functions for working with strings;
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a few examples are shown below.
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For more information on these and other built-in functions, see the Nix Manual
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(https://nixos.org/manual/nix/stable/language/builtins).
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How long is this string?
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[source]
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....
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nix-repl> builtins.stringLength "supercalifragilisticexpialidocious"
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34
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....
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Given a starting position and a length, extract a substring.
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The first character of a string has index `0`.
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[source]
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....
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nix-repl> builtins.substring 3 6 "hayneedlestack"
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"needle"
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....
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[#convert-to-string]
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Convert an expression to a string.
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[source]
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....
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nix-repl> builtins.toString 7
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"7"
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nix-repl> builtins.toString (3*4 + 1)
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"13"
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....
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