[general]
expose TopLevel

[ast]
StmtList
	Cons    (head, tail)
	Nil

Stmt
	Eval    (expr)
	Assign  (token, expr)

Expr
	BinOp   (lhs, op:BinOp, rhs)
	Decimal (literal)
	Float   (literal)

BinOp
	Or
	And
	EQ
	NE
	LE
	LT
	GE
	GT
	Sub
	Add
	Div
	Mul
	Pow

[grammar]

TopLevel
	| Statements

Statements : StmtList
	| Statement Statements {Cons($1,$2)}
	|                      {Nil}

Statement : Stmt
	| Expr                 {Eval($1)}
	| identifier = Expr    {Assign($1,$3)}

Expr : Expr
	| expr[10]

expr[prec]
	prec = 10 | expr[10] or expr[9] {BinOp($1,Or,$3)}

	prec = 9  | expr[9] and expr[8] {BinOp($1,And,$3)}

	prec = 8  | expr[8] == expr[7]  {BinOp($1,EQ,$3)}
	prec = 8  | expr[8] <> expr[7]  {BinOp($1,NE,$3)}
	prec = 8  | expr[8] <= expr[7]  {BinOp($1,LE,$3)}
	prec = 8  | expr[8] >= expr[7]  {BinOp($1,GE,$3)}
	prec = 8  | expr[8] < expr[7]   {BinOp($1,LT,$3)}
	prec = 8  | expr[8] > expr[7]   {BinOp($1,GT,$3)}

	prec = 7  | expr[7] - expr[6]   {BinOp($1,Sub,$3)}
	prec = 7  | expr[7] + expr[6]   {BinOp($1,Add,$3)}

	prec = 6  | expr[6] / expr[5]   {BinOp($1,Div,$3)}
	prec = 6  | expr[6] * expr[5]   {BinOp($1,Mul,$3)}

	prec = 5  | expr[4] ^ expr[5]   {BinOp($1,Pow,$3)}

	prec = 0  | prim_expr

	prec > 0  | expr[prec-1]

prim_expr
	| decimal      {Decimal($1)}
	| float        {Float($1)}
	| ( expr[10] ) {$2}