Original author(s) | Daan Leijen, Paolo Martini, Antoine Latter |
---|---|
Developer(s) | Herbert Valerio Riedel, Derek Elkins, Antoine Latter, Roman Cheplyaka, Ryan Scott |
Initial release | November 2, 2006[1] |
Stable release | 3.1.14.0
/ August 10, 2019[2]
|
Repository |
github |
Written in | Haskell |
Operating system | Linux, macOS, Windows |
Platform | Haskell Platform |
Type | Parser combinator, Library |
License | BSD-3 |
Website |
hackage |
Parsec is a library for writing parsers in Haskell. [3] It is based on higher-order parser combinators, so a complicated parser can be made out of many smaller ones. [4] It has been reimplemented in many other languages, including Erlang, [5] Elixir, [6] OCaml, [7] Racket, [8] and F#, [9] [10] as well as imperative languages such as C#, [11] and Java. [12]
Because a parser combinator-based program is generally slower than a parser generator-based program,[ citation needed] Parsec is normally used for small domain-specific languages, while Happy is used for compilers such as GHC. [13]
Other Haskell parser combinator libraries that have been derived from Parsec include Megaparsec [14] and Attoparsec. [15]
Parsec is free software released under the BSD-3-Clause license. [16]
Parsers written in Parsec start with simpler parsers, such as ones that recognize certain strings, and combine them to build a parser with more complicated behavior. For example, digit
parses a digit, and string
parses a specific string (like "hello"
).
Parser combinator libraries like Parsec provide utility functions to run the parsers on real values. A parser to recognize a single digit from a string can be split into two functions: one to create the parser, and a main
function that calls one of these utility functions (parse
in this case) to run the parser:
import Text.Parsec -- has general parsing utility functions
import Text.Parsec.Char -- contains specific basic combinators
type Parser = Stream s m Char => ParsecT s u m String
parser :: Parser
parser = string "hello"
main :: IO ()
main = print (parse parser "<test>" "hello world")
-- prints 'Right "hello"'
We define a Parser
type to make the type signature of parser
easier to read. If we wanted to alter this program, say to read either the string "hello"
or the string "goodbye"
, we could use the operator <|>
, provided by the Alternative
typeclass, to combine two parsers into a single parser that tries either:
parser = string "hello" <|> string "goodbye"
Original author(s) | Daan Leijen, Paolo Martini, Antoine Latter |
---|---|
Developer(s) | Herbert Valerio Riedel, Derek Elkins, Antoine Latter, Roman Cheplyaka, Ryan Scott |
Initial release | November 2, 2006[1] |
Stable release | 3.1.14.0
/ August 10, 2019[2]
|
Repository |
github |
Written in | Haskell |
Operating system | Linux, macOS, Windows |
Platform | Haskell Platform |
Type | Parser combinator, Library |
License | BSD-3 |
Website |
hackage |
Parsec is a library for writing parsers in Haskell. [3] It is based on higher-order parser combinators, so a complicated parser can be made out of many smaller ones. [4] It has been reimplemented in many other languages, including Erlang, [5] Elixir, [6] OCaml, [7] Racket, [8] and F#, [9] [10] as well as imperative languages such as C#, [11] and Java. [12]
Because a parser combinator-based program is generally slower than a parser generator-based program,[ citation needed] Parsec is normally used for small domain-specific languages, while Happy is used for compilers such as GHC. [13]
Other Haskell parser combinator libraries that have been derived from Parsec include Megaparsec [14] and Attoparsec. [15]
Parsec is free software released under the BSD-3-Clause license. [16]
Parsers written in Parsec start with simpler parsers, such as ones that recognize certain strings, and combine them to build a parser with more complicated behavior. For example, digit
parses a digit, and string
parses a specific string (like "hello"
).
Parser combinator libraries like Parsec provide utility functions to run the parsers on real values. A parser to recognize a single digit from a string can be split into two functions: one to create the parser, and a main
function that calls one of these utility functions (parse
in this case) to run the parser:
import Text.Parsec -- has general parsing utility functions
import Text.Parsec.Char -- contains specific basic combinators
type Parser = Stream s m Char => ParsecT s u m String
parser :: Parser
parser = string "hello"
main :: IO ()
main = print (parse parser "<test>" "hello world")
-- prints 'Right "hello"'
We define a Parser
type to make the type signature of parser
easier to read. If we wanted to alter this program, say to read either the string "hello"
or the string "goodbye"
, we could use the operator <|>
, provided by the Alternative
typeclass, to combine two parsers into a single parser that tries either:
parser = string "hello" <|> string "goodbye"