Reply-To: "Richard H. McCullough" <rhm@cdepot.net>
From: "Richard H. McCullough" <rhm@volcano.net>
To: "KR-language" <KR-language@YahooGroups.com>
Cc: "Apollo, Adrian" <thinkonaut@yahoo.com>,
	"Latimer, Richard S." <rslatimer@comcast.net>,
	"Jetton, Merlin" <merjet@comcast.net>
Subject: MKE 7.0 new syntax: name[char]
Date: Sun, 14 Aug 2005 13:10:09 -0700
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Why the new syntax?  When I invented MKR in 1996,
I decided NOT to allow name[char] because it is 
not English-like.  I have three reasons for
changing my mind.  First, it is a convenient 
shorthand, and useful for working with lists.
Second, I also want MKR to be UNIX-shell-like,
and modern versions of the UNIX shell include
associative arrays.  Third, I am willing to have
some mathematics-like features in MKR.

Here is a brief summary of the new features.
These new forms

Dick[sex] := male;
x := Bob[sex];
Dick[sex] := Bob[sex];

are equivalent to these old forms

Dick has sex=male;
x := Bob has sex=?;
x := Bob has sex=?; Dick has sex=$x;

Here are a couple of examples using lists

x isu list of number;
y isu list of color;
x isall 1,2,3,4,5;
y isall red,blue,green;
z := x[2];     # 2
y[3] := $z;    # 2
y[2] := x[-1]; # 5

The last three statements are equivalent to

z := do list member from x,2 done;
do list member od $z to y,3 done;
do list member from x,-1 to y,2 done;

where "list member" is a method supplied
as part of the MKE system.
(See http://rhm.cdepot.net/kb/method.def)


Dick McCullough
knowledge := man do identify od existent done;
knowledge haspart proposition list;
http://rhm.cdepot.net/