Toy calculator for my talk on compilers at Coderfaire 2013. Try it out.
The grammar is:
PrimaryExpr:
Number
Name
( Expr )
MulExpr :
NegExpr
NegExpr * NegExpr ...
NegExpr / NegExpr ...
Expr :
MulExpr
MulExpr + MulExpr
MulExpr - MulExpr