Rationale for some idiosyncratic conventions in Prolog?

From: Brian Hulley (brianh_at_metamilk.com)
Date: 02/27/05

  • Next message: tmp123: "Re: modifying a given list." 
    Date: 27 Feb 2005 01:57:28 -0800

    Hi -
    I'm wondering why equality and inequality under the standard order is
    specified by using X == Y and X \==Y instead of X @= Y and X @\= Y when
    all the inequalities have the convention that the comparison functor
    starts with a @ sign.

    Also, why does compare(Symbol, X, Y) return '>' '<' or '=' instead of
    '@>' '@<' or '==' since the first 3 symbols have nothing in common when
    converted to predicates for their respective functors of arity 2: '='
    means unification and '<' means arithmetic less-than.

    I'm just wondering since idiosyncracies like these are what can make it
    difficult for a beginner to understand Prolog, and it seems a great
    pity if we have to perperuate these badly thought out conventions just
    for historical reasons (like the terribly ill precedence of bitwise & |
    in C, C++, C#, Java etc which means compilers always have to issue a
    warning because the standard precedence is never what you'd expect (& |
    ~ should bind tighter than any other arithmetic ops since they are much
    "closer to the metal"))

    Would it be worth modifying the ISO standard?

  • Next message: tmp123: "Re: modifying a given list."

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