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[Ömer Sinan Ağacan <omeragacan AT gmail.com>]

Dear K users and developers,

I hope this is the right place to ask user questions. I just started
learning K and I'm having trouble understanding some parts. I actually
have a huge list of questions in mind but for now I want to ask only a
portion of them. Please excuse me if I'm sending this to an
inappropriate list.

Let's say I have this K program: (btw, sorry if I'm using some
terminology wrong and please correct me if I'm wrong. this is my first
K code ever)


    module CONCAT-SYNTAX

      syntax Concat ::= Concat1 ";" Concat
                      | "end"

      syntax Concat1 ::= Id
                      |  "[" Concat "]" // quotation
                      |  Int
                      |  "printSomethingRandom"

    endmodule

    module CONCAT

      imports CONCAT-SYNTAX

      configuration
        <k> $PGM:Concat </k>
        <out stream="stdout"> .List </out>
        <someList> .List </someList>
        <someMap> .Map </someMap>

      rule <k> (printSomethingRandom;Cs) => Cs </k>
           <out> ... . => ListItem(N) </out>
           <someList> ... . => ListItem(N) </someList>
             when fresh(N:Nat)

      rule <k> (I:Id;Cs) => Cs </k>
           <someList> ... . => ListItem(I) </someList>

      rule <k> (I:Int;Cs) => Cs </k>
           // if I remove the part below this rule works fine
           <someMap> ... I |-> (_ => N) ... </someMap>
            when fresh(N:Nat)

      rule <k> end => . </k>

    endmodule


(this is going to be a concatenative language like Forth, PostScript,
Joy, Cat, Factor etc. when it's done)

Now let me list my questions about this program:

  * Let's say I changed the separator in Concat syntax from ";" to "
". Now how can I match it in rules? Simply changing ; characters with
` ` (space character) fails with "syntax error". Interestingly, if I
change it with "-" instead of " ", it works fine. I don't understand
how to use space character in patterns in rules.

  * Is there a reference manual etc. for matching rules to manipulate
data structures like Map/List/Bag etc.? In this code, for some reason
3. rule doesn't work. This is probably because of a mistake in
matching syntax in <someMap> part of the rule. (because removing that
part makes it work) I copied that code from Imp implementation which
is defined in K tutorials, but for some reason same syntax doesn't
work for me.

  * Let's say I'm running this program:

        ➜  concat  cat test.con
        printSomethingRandom;thisIsAnIdentifier;10;end
        ➜  concat  krun --no-config test.con
        ➜  concat  krun test.con
        <k>
            10 ; end
        </k>
        <someList>
            ListItem(#symNat(1))
            ListItem(thisIsAnIdentifier)
        </someList>
        <out>
            ListItem(#ostream ( 1 ))
            ListItem(#buffer ( "" ))
            ListItem(#symNat(1))
        </out>
        <someMap>
            .Map
        </someMap>

    as you can see, even though I'm adding some elements to out list,
and out configuration is marked as an output stream, this program
doesn't really print anything. Why is that?

  * Let's say I'm using built-in list syntax instead of `Concat1 ";"
Concat` syntax I used in first syntax declaration: `List{Concat1,
";"}`. Now how should I change my rules in order to match this new
syntax?


Thanks,


---
Ömer Sinan Ağacan
http://osa1.net