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48 lines
878 B
Text
48 lines
878 B
Text
= Let expressions
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A `let` expression defines a value with a local scope.
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[source]
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....
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nix-repl> let x = 3; in x*x
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9
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nix-repl> let x = 3; y = 2; in x*x + y
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11
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....
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You can also nest `let` expressions.
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The previous expression is equivalent to the following.
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[source]
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....
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nix-repl> let x = 3; in let y = 2; in x*x + y
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11
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....
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[IMPORTANT]
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====
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A variable defined inside a `let` expression will "shadow" an outer variable with the same name.
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[source]
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....
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nix-repl> x = 100
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nix-repl> let x = 3; in x*x
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9
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nix-repl> let x = 3; in let x = 7; in x+1
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8
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....
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====
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A variable in a let expression can refer to another variable in the expression.
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This is similar to how recursive attribute sets work.
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[source]
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....
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nix-repl> let x = 3; y = x + 1; in x*y
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12
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....
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// TODO Discuss inheriting attributes https://nixos.org/manual/nix/stable/language/constructs#inheriting-attributes
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