GoMathExecutor

calc := executor.NewCalc()
calc.AddOperators(executor.MathOperators) // Loads default MathOperators (see: defaults.go)
calc.Prepare("2+2*2") // Prepare expression
calc.Execute(nil) // == 6, nil
calc.Prepare("x * (y+z)") // Prepare another expression with variables
calc.Execute(map[string]float64{
    "x": 3,
    "y": 2,
    "z": 1,
}) // == 9, nil