forked from orion/obsidian
46 lines
1.1 KiB
Markdown
46 lines
1.1 KiB
Markdown
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[[Functions]] are curried in PureScript, meaning that "a function of 2 arguments" is actually "a function of 1 argument, returning a function of 1 argument."
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This allows you to call many functions point-free, and think in terms of "building up to a conclusion" rather than "i need everything at once."
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e.g.
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```haskell
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add :: Int -> Int -> Int
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-- ...
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add2 :: Int -> Int
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add2 n = add 2 n
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```
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is equivalent to
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```haskell
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add :: Int -> Int -> Int
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-- ...
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add2 :: Int -> Int
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add2 = add 2
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```
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Walking through this:
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`add` has type `Int -> Int -> Int`
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if we give `add` a single `Int` argument, it will return a function of type `Int -> Int`. This function is the "second half" of `add`, waiting for it's second argument. Since `Int -> Int` is the type of `add2`, we can simply say `add2 = add 2`.
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> [!info]
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> as a rule, any time a function's last argument is passed as the last argument to another function, you can remove both.
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> ```haskell
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> f a = g b c a
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>
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> \a -> g b c a
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>
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> f a = g $ h a
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> ```
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> can be written as
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> ```haskell
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> f = g b c
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>
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> g b c
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>
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> f = g <<< h
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> ```
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