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README.md
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@ -21,8 +21,8 @@
* [Contribution](#contribution)
* [License](#license)
This is an industrial-strength monadic parser combinator library. Megaparsec is
a fork of [Parsec](https://github.com/aslatter/parsec) library originally
This is an industrial-strength monadic parser combinator library. Megaparsec
is a fork of [Parsec](https://github.com/aslatter/parsec) library originally
written by Daan Leijen.
## Features
@ -34,19 +34,23 @@ comprehensive documentation, see the
### Core features
The package is built around `MonadParsec`, a MTL-style monad transformer. All
tools and features work with any instance of `MonadParsec`. You can achieve
various effects combining monad transformers, i.e. building monad
stack. Since most common monad transformers like `WriterT`, `StateT`,
`ReaderT` and others are instances of `MonadParsec`, you can wrap `ParsecT`
*in* these monads, achieving, for example, backtracking state.
The package is built around `MonadParsec`, a MTL-style monad
transformer. All tools and features work with any instance of
`MonadParsec`. You can achieve various effects combining monad transformers,
i.e. building monad stack. Since most common monad transformers like
`WriterT`, `StateT`, `ReaderT` and others are instances of `MonadParsec`,
you can wrap `ParsecT` *in* these monads, achieving, for example,
backtracking state.
On the other hand `ParsecT` is instance of many type classes as well. The most
useful ones are `Monad`, `Applicative`, `Alternative`, and `MonadParsec`.
On the other hand `ParsecT` is instance of many type classes as well. The
most useful ones are `Monad`, `Applicative`, `Alternative`, and
`MonadParsec`.
The module [`Text.Megaparsec.Combinator`](https://hackage.haskell.org/package/megaparsec/docs/Text-Megaparsec-Combinator.html) (its functions are included in
`Text.Megaparsec`) contains traditional, general combinators that work with
any instance of `Alternative` and some even with instances of `Applicative`.
The module
[`Text.Megaparsec.Combinator`](https://hackage.haskell.org/package/megaparsec/docs/Text-Megaparsec-Combinator.html)
(its functions are included in `Text.Megaparsec`) contains traditional,
general combinators that work with any instance of `Alternative` and some
even with instances of `Applicative`.
Role of `Monad`, `Applicative`, and `Alternative` should be obvious, so
let's enumerate methods of `MonadParsec` type class. The class represents
@ -103,13 +107,13 @@ categories:
characters of the same kind. This includes `newline`, `crlf`, `eol`,
`tab`, and `space`.
* *Parsers corresponding to categories of characters* parse single characters
that belongs to certain category of characters, for example: `controlChar`,
`spaceChar`, `upperChar`, `lowerChar`, `printChar`, `digitChar`, and
others.
* *Parsers corresponding to categories of characters* parse single character
that belongs to certain category of characters, for example:
`controlChar`, `spaceChar`, `upperChar`, `lowerChar`, `printChar`,
`digitChar`, and others.
* *General parsers* that allow you to parse a single character you specify or
one of given characters, or any character except for given ones, or
* *General parsers* that allow you to parse a single character you specify
or one of given characters, or any character except for given ones, or
character satisfying given predicate. Case-insensitive versions of the
parsers are available.
@ -130,8 +134,8 @@ Megaparsec has a solution for parsing of expressions. Take a look at
[`Text.Megaparsec.Expr`](https://hackage.haskell.org/package/megaparsec/docs/Text-Megaparsec-Expr.html). You have to import the module explicitly, it's not
included in the `Text.Megaparsec` module.
Given a table of operators that describes their fixity and precedence, you can
construct a parser that will parse any expression involving the
Given a table of operators that describes their fixity and precedence, you
can construct a parser that will parse any expression involving the
operators. See documentation for comprehensive description of how it works.
### Lexer
@ -144,11 +148,11 @@ in the past, this module “fixes” its particularly inflexible
`Text.Megaparsec.Lexer` is intended to be imported qualified, it's not
included in `Text.Megaparsec`. The module doesn't impose how you should
write your parser, but certain approaches may be more elegant than
others. An especially important theme is parsing of white space, comments,
others. An especially important theme is parsing of white space, comments,
and indentation.
The design of the module allows you quickly solve simple tasks and doesn't get
in your way when you want to implemented something less standard.
The design of the module allows you quickly solve simple tasks and doesn't
get in your way when you want to implemented something less standard.
## Documentation