A fast Haskell library for parsing ByteStrings
Questions tagged [attoparsec]
131 questions
3
votes
1 answer
finally tagless parsing and recursive monadic actions
i deserialize a data structure from disc in the finally tagless style. i.e.
class SYM repl where
a :: repl
include :: FilePath -> repl
myParser :: SYM r => Parser r
the language i am parsing has include directives.
i am using attoparsec…
ibotty
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3
votes
1 answer
Does Data.Attoparsec.ByteString use "zero copy"ing?
Take for example takeWhile. Internally it uses span.
Does that mean it just references the input bytestring? Probably not, if so, is there a way to achieve this?
The motivating usecase is a large (>2gb) file that I want to map into memory and…
fho
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3
votes
1 answer
How can you make the latest Attoparsec match strings in a case-insensitive way?
attoparsec 0.72 had this function but it seems to have disappeared in later versions:
stringTransform :: (ByteString -> ByteString) -> ByteString -> Parser ByteString
"Match a literal string, after applying a transformation to both it and the…
dan
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3
votes
1 answer
Attoparsec: Skipping bracketed terms?
I'm trying to make large TSV files with JSON in the 5th column suitable for import to mongoDB.
In particular I want to change top level and only top level key fields to _id. This is what I have so far, it seems to work but is slow:
{-# LANGUAGE…
FAWS
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- 3
3
votes
1 answer
Parsing Karva notation in haskell
Karva notation is used in Gene Expression Programming to represent mathematical expressions.
See here http://www.gene-expression-programming.com/Tutorial002.asp
You create an expression tree by reading the off the gene and filling in nodes from…
michael.mcclintock
- 41
- 1
3
votes
1 answer
How to properly add IO to attoparsec Parser?
I want to do some tracing/debugging in my attoparsec parser. Here's minimal [not] working example:
import Data.Text as T
import Data.Attoparsec.Text
import Data.Attoparsec.Combinator
import Control.Applicative ((<*), (*>))
parseSentences :: Parser…
wiz
- 499
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- 17
2
votes
2 answers
Equivalent of attoparsecs `inClass` in Parsec
I am translating some code from attoparsec to Parsec, because the parser needs to produce better error messages. The attoparsec code uses inClass (and notInClass) extensively. Is there a similar function for Parsec that lets me translate…
dflemstr
- 25,947
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2
votes
1 answer
Incomplete input using endOfInput parser
Consider the string "(=x250) toto e", and the function:
charToText :: Char -> Text
charToText c = pack [c]
The string is successfully parsed by:
mconcat <$> manyTill (charToText <$> anyChar) (char 'e')
with the expected result "(=x250) toto…
vkubicki
- 1,104
- 1
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2
votes
1 answer
Parsing custom fields with Cassava and Attoparsec
I have a CSV with fields in it which contain unit values which I have to parse out. As a simple example:
data EValue = Farads Double | MicroFarads Double | PicoFarads Double
Thus I need to parse something like the following:
parseEValue = farads…
GTF
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2
votes
2 answers
Convert Attoparsec parser to parse from another string type
Is there some "easy" way (e.g. something I am missing in Attoparsec or some other library) to convert a defined Attoparsec parser that parses from ByteString to the one that parses from Text?
For example I have:
import…
esp
- 7,314
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2
votes
2 answers
Performance analysis of a fold using map and ByteString keys
I have a little script to read in, parse and derive some kind of interesting (not really) statistics from an apache log file. So far I've made two simple options, the total number of bytes sent in all requests in the log file, and a top 10 of the…
Johanna Larsson
- 10,531
- 6
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- 50
2
votes
1 answer
Matching values that carry onto multiple following lines with attoparsec
I'm trying to parse the following:
message: 123 test
abc xys
messageA: hmm
messageA: testing
messageB: aueo
qkhwueoaz
Into something like:
[
("message", "123 test\nabcxyz"),
, ("messageA", "hmm")
, ("messageA","testing")
,…
Chris Stryczynski
- 30,145
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2
votes
1 answer
Conduit parser is interrupted prematurely
I'm working on a program where I need to parse data from a USB connection and write it to a circular buffer.
The issue I keep running into is that the parser is not consuming the input. Do I need to use another operator to connect the parser conduit…
SwiftsNamesake
- 1,540
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2
votes
0 answers
CSV Parsing Issue with Attoparsec
Here is my code that does CSV parsing, using the text and attoparsec
libraries:
import qualified Data.Attoparsec.Text as A
import qualified Data.Text as T
-- | Parse a field of a record.
field :: A.Parser T.Text -- ^ parser
field = fmap T.concat…
Daniel Lovasko
- 471
- 2
- 10
2
votes
0 answers
Is there a way to force an attoparsec not to backtrack?
I've written some parsers using Attoparsec but only now realised that I don't always want them to backtrack on failure, but attoparsec parsers always backtrack on failure.
Is there a way to force a parser not to backtrack?
For example, this…
askoufis
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- 1