CD-1 evolution

This extension adds grouping disambiguation to the CD language, and allows you to write applications without parentheses.

CBS currently uses the SDF3 meta-language for disambiguation, enclosing references to embedded grammar sorts and productions in back-ticks.

Changes

1. Replace:

   | exp '(' exp ')'
   

   by:

   | exp  exp
   

2. Replace:

   Rule eval[[ E1 '(' E2 ')' ]] =
   

   by:

   Rule eval[[ E1 E2 ]] =
   

Additions

Syntax SDF
/*
context-free syntax
``exp ::= 'lambda' id '.' exp`` {longest-match}
``exp ::= exp exp`` {left}
``exp ::= 'let' id '=' exp 'in' exp`` {longest-match}

context-free priorities
``exp ::= exp exp``
> {
``exp ::= 'lambda' id '.' exp``
``exp ::= 'let' id '=' exp 'in' exp``
}
*/

Lexis SDF
/*
lexical syntax
  ``id`` = ``keyword`` {reject}

lexical restrictions
  ``id``  -/- [a-z0-9]
  ``int`` -/- [0-9]
*/

You could put disambiguation specifications in a separate file, e.g., named CD-Disambiguation.cbs

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