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[<isaacdefrain AT gmail.com>]

Hello again,

I recently asked about cellbags and functions and have since produced a
minimal example which demonstrates the idea I'm hoping to capture and gives
rise to the same error as before.

Basically, I would like to define a function which directly uses the contents
of a CellBag as input, but I always get a compilier error.

Here's the example:

// CellBag Function minimal example
require "domains.k"

module CELLBAG-SYNTAX
  import DOMAINS

  syntax  Term ::= Int
                 | "[" Terms "]"
                 | "SumBeta"      [token]
  syntax Terms ::= Term
                 > Term "," Terms [right]

  syntax KItem ::= Int

endmodule

module CELLBAG
  import CELLBAG-SYNTAX

  configuration
  <T>
    <k> $PGM:Term </k>
    <alpha>
      <beta multiplicity="*">
        .K
      </beta>
    </alpha>
  </T>

  syntax KResult ::= Int

  syntax BetaCell
  syntax BetaCellBag

  // add Term list contents to <beta/> cells
  rule <k> [I:Int , T:Terms] => [T] ...</k>
       (.Bag => <beta> I </beta>)
    // call SumBeta at the end
  rule <k> [I:Int] => SumBeta ...</k>
       (.Bag => <beta> I </beta>)

  // sum contents of <beta/> cells
  rule <k> SumBeta => sum(B) </k>
       <alpha> B => .Bag </alpha>

  // sum contents of <beta/> cells
  syntax Int ::= "sum(" BetaCellBag ")" [function]
  rule sum( .BetaCellBag ) => 0
  rule sum( <beta> I:Int </beta> B:BetaCellBag ) => I +Int sum(B)

endmodule

Kompiling results in the error:
[Error] Compiler: Had 1 parsing errors.
[Error] Inner Parser: Parse error: unexpected token 'B'.
        Source(path/to/cellbag.k)
        Location(50,34,50,35)

This error is due to the second rule for the "sum" function (i.e. `rule
sum( <beta> I:Int </beta> B:BetaCellBag ) => I +Int sum(B)`). If instead, this
rule is changed to `rule sum( <beta> I:Int </beta> ) => I`, there is no
compilation error and programs execute as expected.

I am using the Java backend to kompile and RV-K version 1.0-SNAPSHOT
Git revision: 1e310cd
Git branch: UNKNOWN
Build date: Thu Jan 31 03:38:17 EST 2019

I would greatly appreciate any insights you may have! Thank you.

Best,

Isaac