FParsec is an F# adaptation of Parsec. It can parse context-sensitive, infinite look-ahead grammars. The basic idea behind combinator parsing is to compose parsers for higher-level grammar expressions from simple atomic parsers. A parser combinator library provides those predefined atomic parsers and the means to combine them into larger units. In the case of FParsec all parsers are F# functions, functions that can be combined with higher-level functions, so-called "combinators". The parser combinator approach as implemented by FParsec has a number of advantages * Power. Since parsers are first-class values within the language, users can draw on the full power of F# to implement their parsers. * Extensibility. FParsec has a modular design that is very amenable to extensions. No matter how complicated your grammar is, you will always be able to parse it * Quality of error messages. Parsers implemented with FParsec generate intelligible error messages