19 lines
549 B
OCaml
19 lines
549 B
OCaml
(** A stack action (pop is run first, then push sequentially) *)
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type 'a t =
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{ pop : int
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; push : 'a list
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}
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let merge lhs rhs =
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(* merge lhs.push and rhs.pop first *)
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let rec compensate push pop = match (push, pop) with
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| (_, 0) -> (push, pop)
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| ([], _) -> (push, pop)
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| (_::xs, _) -> compensate xs (pop - 1)
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in let (push, pop) = compensate lhs.push rhs.pop in
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{ pop = lhs.pop + pop; push = List.append push rhs.push; }
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let empty = { pop = 0; push = []; }
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let map f sta = { pop = sta.pop; push = List.map f sta.push; }
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