github.com/PaesslerAG/gval (go): Package gval provides a generic expression language. All functions, infix and prefix operators can be replaced by composing languages into a new one.  The package contains concrete expression languages for common application in text, arithmetic, decimal arithmetic, propositional logic and so on. They can be used as basis for a custom expression language or to evaluate expressions directly.
Keywords: evaluate-expressions|evaluation|expression-evaluator|expression-language|go|godoc|golang|gval|parser|parsing