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Questions tagged [parsec]

Parsec is an industrial-strength, monadic parser combinator library for Haskell.

Parsec is an industrial strength, monadic parser combinator library for Haskell. Parsec lets you construct parsers by combining higher-order Combinators to create larger expressions. Combinator parsers are written and used within the same programming language as the rest of the program. The parsers are first-class citizens of the language , unlike Happy parsers, which must be generated via a preprocessor.

More information about Parsec, including usage examples, can be found on the Parsec website.

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attoparsec or parsec in haskell

I have to parse some files and convert them to some predefined datatypes. Haskell seems to be providing two packages for that: attoparsec parsec What is the difference between the two of them and which one is better suited for parsing a text file…
Sibi
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What are the benefits of applicative parsing over monadic parsing?

There seems to be a consensus that you should use Parsec as an applicative rather than a monad. What are the benefits of applicative parsing over monadic parsing? style performance abstraction Is monadic parsing out?
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Should I use a lexer when using a parser combinator library like Parsec?

When writing a parser in a parser combinator library like Haskell's Parsec, you usually have 2 choices: Write a lexer to split your String input into tokens, then perform parsing on [Token] Directly write parser combinators on String The first…
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What's the difference between Text.ParserCombinators.Parsec and Text.Parsec

Text Text.Parsec Text.Parsec.ByteString Text.Parsec.ByteString.Lazy Text.Parsec.Char Text.Parsec.Combinator Text.Parsec.Error Text.Parsec.Expr Text.Parsec.Language …
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Parsec vs Yacc/Bison/Antlr: Why and when to use Parsec?

I'm new to Haskell and Parsec. After reading Chapter 16 Using Parsec of Real World Haskell, a question appeared in my mind: Why and when is Parsec better than other parser generators like Yacc/Bison/Antlr? My understanding is that Parsec creates a…
Ning Wang
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Can parser combinators be made efficient?

Around 6 years ago, I benchmarked my own parser combinators in OCaml and found that they were ~5× slower than the parser generators on offer at the time. I recently revisited this subject and benchmarked Haskell's Parsec vs a simple hand-rolled…
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Using Parsec with Data.Text

Using Parsec 3.1, it is possible to parse several types of inputs: [Char] with Text.Parsec.String Data.ByteString with Text.Parsec.ByteString Data.ByteString.Lazy with Text.Parsec.ByteString.Lazy I don't see anything for the Data.Text module. I…
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What is the advantage of using a parser generator like happy as opposed to using parser combinators?

To learn how to write and parse a context-free grammar I want to choose a tool. For Haskell, there are two big options: Happy, which generates a parser from a grammar description and *Parsec, which allows you to directly code a parser in…
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Full parser examples with parsec?

I'm trying to make a parser for a simple functional language, a bit like Caml, but I seem to be stuck with the simplest things. So I'd like to know if there are some more complete examples of parsec parsers, something that goes beyond "this is how…
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Parsec: Applicatives vs Monads

I'm just starting with Parsec (having little experience in Haskell), and I'm a little confused about using monads or applicatives. The overall feel I had after reading "Real World Haskell", "Write You a Haskell" and a question here is that…
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How do Scala parser combinators compare to Haskell's Parsec?

I have read that Haskell parser combinators (in Parsec) can parse context sensitive grammars. Is this also true for Scala parser combinators? If so, is this what the "into" (aka ">>") function is for? What are some strengths/weaknesses of Scala's…
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Parsec: difference between "try" and "lookAhead"?

What is the difference between "try" and "lookAhead" functions in parsec?
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Why does Parsec not use Control.Applicative operators

Using Control.Applicative is very useful with Parsec, but you need to always hide <|> and similar objects as they conflict with Parsec's own: import Control.Applicative hiding ((<|>), many, optional) import Text.Parsec.Combinator import…
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User state in Parsec

I'm parsing an expression using Parsec and I want to keep track of variables in these expressions using the user state in Parsec. Unfortunately I don't really get how to do it. Given the following code: import Data.Set as Set inp = "$x = $y +…
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Haskell/Parsec: how do I use Text.Parsec.Token with Text.Parsec.Indent (from the indents package)

The indents package for Haskell's Parsec provides a way to parse indentation-style languages (like Haskell and Python). It redefines the Parser type, so how do you use the token parser functions exported by Parsec's Text.Parsec.Token module, which…
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