GRR example: translate a Pascal-ish language to C.
includes constant folding optimizer!!!


main:	X:stats				= program(X):c
	X				= "error!":stderr
stats:	X:stat ";" Y:stats		= [X|Y]
	X:stat				= X
stat:	"begin" X:stats "end"		= X
	X:ident ":=" Y:exp		= assign(X,Y)
	"if" X:comp "then" Y:stat	= if(X,Y)
	"while" X:comp "do" Y:stat	= while(X,Y)
comp:	X:exp "=" X:exp			= eq(X,Y)
exp:	X:term "+" Y:exp		= plus(X,Y)
	X:term				= X
term:	X:factor "*" Y:term		= times(X,Y)
	X:factor			= X
factor:	"(" X:exp ")"			= X
	X:ident				= id(X)
	"[0-9]+"/X			= int(X:val)
ident:	"[a-c]"/X			= X
c:	program(X:c)			= "int a,b,c;\nmain() {\n" X "}\n"
	[X:c|Y:c]			= X ";\n" Y
	assign(X:c,Y:opt:c)		= X "=" Y
	if(X:c,Y:c)			= "if (" X ") {\n" Y "}"
	while(X:c,Y:c)			= "while (" X ") {\n" Y "}"
	eq(X:opt:c,Y:opt:c)		= X "==" Y
	plus(X:c,Y:c)			= X "+" Y
	times(X:c,Y:c)			= X "*" Y
	ident(X)			= X
	int(X)				= X:str
opt:	plus(X:opt/int(Y),Z:opt/int(W))	= int((Y,W):add)
	times(X:opt/int(Y),Z:opt/int(W))= int((Y,W):mul)

would turn:

	while a=1 do
	  begin
	    c:=a*3;
	    if c=16*(8+8) then b:=5+1
	  end

into: (note the optimisations :-)

	int a,b,c;
	main() {
	while (a == 1) {
	c=a*3;
	if (c==256) {
	b=6
	};
	};
	}