import macros
macro case_token(n: stmt): stmt =
  # creates a lexical analyzer from regular expressions
  # ... (implementation is an exercise for the reader :-)
  nil

case_token: # this colon tells the parser it is a macro statement
of r"[A-Za-z_]+[A-Za-z_0-9]*":
  return tkIdentifier
of r"0-9+":
  return tkInteger
of r"[\+\-\*\?]+":
  return tkOperator
else:
  return tkUnknown
  
case_token: inc i