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CONST east = 0; south = 1; west = 2; north = 3; directions = 4; TYPE Direction = SHORTINT; (* east..north *) PROCEDURE TurnRight(dir: Direction) : Direction; BEGIN RETURN (dir + 1) MOD directions END TurnRight; PROCEDURE TurnLeft(dir: Direction) : Direction; BEGIN RETURN (dir - 1) MOD directions END TurnLeft; |
An diesem Beispiel zeigt sich die wohltuende Symmetrie
der F-Definition und der nach Euklid.
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Bei Verwendung der T-Definition müßte der Rückgabewert
von TurnLeft so berechnet werden: RETURN (dir + directions - 1) MOD directions | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Copyright © 1999 Andreas Borchert, in HTML konvertiert am 29.06.1999 |