67 lines
1.2 KiB
ObjectPascal
67 lines
1.2 KiB
ObjectPascal
program List_monad;
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{$APPTYPE CONSOLE}
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uses
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System.SysUtils;
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type
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TmList = record
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Value: TArray<Integer>;
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function ToString: string;
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function Bind(f: TFunc<TArray<Integer>, TmList>): TmList;
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end;
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function Create(aValue: TArray<Integer>): TmList;
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begin
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Result.Value := copy(aValue, 0, length(aValue));
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end;
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{ TmList }
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function TmList.Bind(f: TFunc<TArray<Integer>, TmList>): TmList;
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begin
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Result := f(self.Value);
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end;
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function TmList.ToString: string;
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var
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i: Integer;
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begin
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Result := '[ ';
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for i := 0 to length(value) - 1 do
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begin
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if i > 0 then
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Result := Result + ', ';
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Result := Result + value[i].toString;
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end;
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Result := Result + ']';
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end;
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function Increment(aValue: TArray<Integer>): TmList;
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var
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i: integer;
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begin
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SetLength(Result.Value, length(aValue));
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for i := 0 to High(aValue) do
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Result.Value[i] := aValue[i] + 1;
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end;
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function Double(aValue: TArray<Integer>): TmList;
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var
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i: integer;
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begin
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SetLength(Result.Value, length(aValue));
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for i := 0 to High(aValue) do
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Result.Value[i] := aValue[i] * 2;
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end;
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var
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ml1, ml2: TmList;
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begin
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ml1 := Create([3, 4, 5]);
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ml2 := ml1.Bind(Increment).Bind(double);
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Writeln(ml1.ToString, ' -> ', ml2.ToString);
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readln;
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end.
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