Expr

Expr is an engine that can evaluate expressions.

The purpose of the package is to allow users to use expressions inside configuration for more complex logic. It is a perfect candidate for the foundation of a business rule engine. The idea is to let configure things in a dynamic way without recompile of a program:

# Get the special price if
user.Group in ["good_customers", "collaborator"]

# Promote article to the homepage when
len(article.Comments) > 100 and article.Category not in ["misc"]

# Send an alert when
product.Stock < 15

Inspired by

• Symfony's The ExpressionLanguage component,
• Rob Pike's talk Lexical Scanning in Go.

Install

go get -u github.com/antonmedv/expr

Documentation

• See godoc.org/github.com/antonmedv/expr for developer documentation,
• See The Expression Syntax page to learn the syntax of the Expr expressions.

License

MIT