24 lines
701 B
Plaintext
24 lines
701 B
Plaintext
-- Cons patterns divide a list or string value into a head (the first element) and a tail (the rest of the elements).
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-- We can make an identity for lists or strings like so:
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consid(hd::tl) -> hd::tl.
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-- it deconstructs and then immediately reconstructs the value.
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print(consid([1, 2, 3])). -- [1, 2, 3]
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-- Cons patterns are polymorphic, depending on the value they're matching.
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-- "x"::xs will match both "x" and ["x"]. Let us demonstrate:
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f("x"::xs) -> xs.
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print(f("xy")). -- "y"
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print(f(["x", "y"])). -- ["y"]
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-- the same works for chaining cons patterns, so:
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-- "x"::"y"::tl will match "xy" and ["x", "y"]
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g("x"::"y"::tl) -> tl.
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print(g("xyz")). -- "z"
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print(g(["x", "y", "z"])). -- ["z"] |