Russ Abbott wrote:
As a new Mozart-Oz user, I have what's probably a simple question. (I
have a number of simple questions, but I'll start with this one.)
Why is it necessary to declare local variables in procedures and
functions. Considering how much effort was put into making Oz an easy
language to write, why force explicit declarations? After all, the
compiler could implicitly declare any variable at the procedure level
if it is not otherwise declared. This would parallel the way
that variables on the right-hand-side of prolog clauses are implicitly
declared.
You raise several issues here! Explicit declarations avoid the bug when
the variable already exists
in the surrounding context. BTW, this does not mean you have to do any
extra typing, since you
can declare and initialize the variable at the same time, e.g.:
local X=12 in {Browse X} end
Prolog does not have lexical scoping (it is a *flat* language). All
variables in the clause body are
implicitly universally quantified. This is not so nice if you want to
have local variables in a clause
body: you can't!
Thanks.
By the way, to push myself to use Oz, I decided to teach an AI course
with it. My plan is to work our way through the book and use Oz
computational capabilities to write one or more Sudoku solving
programs. If anyone is interested, the course web page is:
http://cs.calstatela.edu/~wiki/index.php/CS-460-1.Fall-2005:Main_Page
<http://cs.calstatela.edu/%7Ewiki/index.php/CS-460-1.Fall-2005:Main_Page>.
This is a wiki. If you have anything useful to add, please do so.
-- Russ Abbott
This looks very nice. Using Oz to solve Sudoku can lead you well into
constraint programming!
Did you see Raphael Collet's program on solving the minesweeper using
constraint
programming: http://www.info.ucl.ac.be/~raph/minesweeper/ (see the MOZ
2004 proceedings,
Springer LNCS 3389).
Peter
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