; -*- Hen -*-

(require-extension lalr)

(define expr-parser
  (lalr-parser

   (output:    expr-parser "expr.grm.scm")

   ;; --- token definitions
   ( ID NUM IF THEN ELSE RPAREN  ;;LET
       (left: + - * /)
       (right: QUESTION COLON)
       (left: < > = >= <=)
       (left: uminus)
       (right: ^ ) 
       (left: LPAREN)
       )
   
   (expr     (NUM)                    : (exact->inexact $1)
             (ID)                     : $1
	     (ID LPAREN RPAREN)       : `(,$1 ())
	     (ID LPAREN args RPAREN)  : `(,$1 (,(reverse $3)))
	     (expr + expr)            : `(,$1 + ,$3)
             (expr - expr)            : `(,$1 - ,$3)
             (expr * expr)            : `(,$1 * ,$3)
             (expr / expr)            : `(,$1 / ,$3)
             (- expr (prec: uminus))  : `(- ,$2)
             (expr ^ expr)            : `(,$1 ^ ,$3)
	     (expr < = expr)          : `(,$1 <=  ,$4)
	     (expr > = expr)          : `(,$1 >=  ,$4)
	     (expr <= expr)           : `(,$1 <=  ,$3)
	     (expr >= expr)           : `(,$1 >=  ,$3)
	     (expr > expr)            : `(,$1 > ,$3)
	     (expr < expr)            : `(,$1 < ,$3)
	     (expr QUESTION expr COLON expr) :  `(if ,$1 then ,$3 else ,$5) 
	     (IF  expr THEN expr ELSE expr)  :  `(if ,$2 then ,$4 else ,$6) 
	     (LPAREN expr RPAREN)     : $2 
	     )

   (args     (expr)                   : (list $1)
             (args expr)              : (cons $2 $1))

  ))