70 lines
1.9 KiB
Standard ML
70 lines
1.9 KiB
Standard ML
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use "operators.sml";
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use "list.sml";
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type FullName = {first: string, middle: string, last: string}
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(* too complex *)
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fun all_except_option (str, lst) =
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if exists str lst
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then SOME $ filter (fn elem => elem <> str) lst
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else NONE
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(* more straightforward *)
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fun all_except_option (str, lst) =
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let
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val filtered = filter (fn elem => elem <> str) lst
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in
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if lst = filtered then NONE else SOME filtered
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end
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(* maybe it's what assigment requires us to do but I don't like it *)
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(* how to get it in 8 lines?! *)
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fun all_except_option (str, lst) =
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let
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fun filter (same_lst, acc) lst =
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case lst of
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[] => (same_lst, acc)
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| head :: tail =>
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if head = str
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then filter (false andalso same_lst, acc) tail
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else filter (same_lst, head :: acc) tail
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in
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case filter (true, []) lst of
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(false, lst) => SOME $ reverse lst
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| (true, _) => NONE
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end
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fun get_substitutions1 (
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substitutions: string list list,
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name: string
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): string list =
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let
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fun collect lst acc =
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case all_except_option (name, lst) of
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NONE => acc
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| SOME names => acc @ names
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in
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fold collect [] substitutions
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end
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(* lol, previous function is already tail recursive 😎 *)
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fun get_substitutions2 (
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substitutions: string list list,
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name: string
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): string list = get_substitutions1(substitutions, name)
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fun similar_names (
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substitutions: string list list,
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{first=first, middle=middle, last=last}: FullName
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): FullName list =
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let
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fun full_substitution name acc =
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{first=name, middle=middle, last=last} :: acc
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in
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get_substitutions1 (substitutions, first)
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|> fold full_substitution []
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|> reverse
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|> cons {first=first, middle=middle, last=last}
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end
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