Checking for a value in a list

From: Mark J Fenbers (Mark.Fenbers_at_noaa.gov)
Date: 03/30/04

  • Next message: Bill Spight: "Re: Checking for a value in a list" 
    Date: Mon, 29 Mar 2004 18:57:55 -0500

    I'm stumbling my first Prolog program. This fact will be obvious when
    you read my question that follows...

    I want to describe that a shift is considered "operational" if the shift
    is among the given list of 'H', 'D', '6', 'HE', or 'E'. My code has
    this:

    operational(Shift) :-
        equals(Shift,'H').
    operational(Shift) :-
        equals(Shift,'D').
    operational(Shift) :-
        equals(Shift,'6').
    operational(Shift) :-
        equals(Shift,'HE').
    operational(Shift) :-
        equals(Shift,'E').

    I understand (perhaps incorrectly) that this code means
    operational(Shift) if Shift equal 'H' or Shift equals 'D' or Shift
    equals '6' or Shift equals 'HE' or Shift equals 'E'. I have a feeling
    that this isn't the best way to check if Shift is among the given list.
    What is a better way?

    Mark 

    

    

    

  • Next message: Bill Spight: "Re: Checking for a value in a list"





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