@hackage ParserFunction0.0.6

ParserFunction provides utilities for parsing and evaluating mathematical expressions. The central parsing function in this package is stringToExpr, which parses a string-expression (e.g. "3*x+2") and returns a Maybe expression tree of type Expr (e.g. Just (Add (Mul (Num 3.0) (Var 'x')) (Num 2.0))). This type is suitable for performing symbolic logic. Expressions can then be evaluated using the function evaluate (e.g. evaluate (fromAscList [("x",2)]) (Add (Mul (Num 3.0) (Var 'x'))) (Num 2.0) would give 8.0). If you wish to evaluate a string-expression without any intermediate symbolic logic operations, simply use the function evaluateExpression (e.g. evaluateExpression "3*x+2" [('x',4)] gives 14.0). More examples of these functions can be found by viewing the source code for this package.