15 lines
575 B
OCaml
15 lines
575 B
OCaml
type ('s, 't, 'a, 'b) lens = ('s -> 'a) * ('b -> 's -> 't)
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type ('s, 'a) lens' = ('s, 's, 'a, 'a) lens
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let lens ~view ~set = view, set
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let view (get, _) = get
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let set (_, put) = put
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let over (get, put) ~f source = put (f (get source)) source
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let compose (outer_get, outer_put) (inner_get, inner_put) =
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(fun source -> inner_get (outer_get source)),
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(fun value source -> outer_put (inner_put value (outer_get source)) source)
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let _1 = (fun (left, _) -> left), (fun left (_, right) -> left, right)
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let _2 = (fun (_, right) -> right), (fun right (left, _) -> left, right)
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