### take Parser Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example of using the take parser.

```Haskell
take 4  -- Gets next 4 bytes
```

--------------------------------

### Basic GET Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A simple GET request to the root of a website.

```http
GET / HTTP/1.1
Host: www.reddit.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
```

--------------------------------

### string Parser Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example of using the string parser.

```Haskell
string "HTTP/" >> take 3  -- Match "HTTP/" then 3 bytes
```

--------------------------------

### parse Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/errors.md

An example demonstrating how to use `parse` and handle its `IResult`.

```haskell
case parse myParser input of
  Done remainder result -> 
    putStrLn $ "Success: " ++ show result
  Fail _ ctxs msg -> 
    putStrLn $ "Error at: " ++ show ctxs ++ ": " ++ msg
  Partial k ->
    -- feed k moreInput
```

--------------------------------

### anyChar Parser Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/text-parsing.md

Example of using anyChar.

```Haskell
anyChar  -- Matches "X", returns 'X'
```

--------------------------------

### parse Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example usage of the parse function.

```Haskell
import Data.Attoparsec.Zepto
import qualified Data.ByteString as BS

result = parse (string "GET" >> take 3) (BS.pack "GET /index")
-- Right " /i"
```

--------------------------------

### Sample HTTP Request

Source: https://github.com/haskell/attoparsec/blob/master/benchmarks/http-request.txt

An example of an HTTP GET request with various headers, suitable for benchmarking.

```http
GET / HTTP/1.1
Host: twitter.com
Accept: text/html, application/xhtml+xml, application/xml; q=0.9, image/webp, */*; q=0.8
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-GB,en-US;q=0.8,en;q=0.6
Cache-Control: max-age=0
Cookie: guest_id=v1%3A139; _twitter_sess=BAh7CSIKZmxhc2hJQz-e1e1; __utma=43838368.452555194.1399611824.1; __utmb=43838368; __utmc=43838368; __utmz=1399611824.1.1.utmcsr=(direct)|utmcmd=(none)
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.86 Safari/537.36
```

--------------------------------

### Example HTTP Request 10

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /hVMVTDdjuY3bQox5.jpg HTTP/1.1
Host: f.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Example HTTP Request 5

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /ixd1C1njpczEWC22.jpg HTTP/1.1
Host: c.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Example HTTP Request 7

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /zT4yQmDxQLbIxK1b.jpg HTTP/1.1
Host: c.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Example HTTP Request 12

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /gZJL1jNylKbGV4d-.jpg HTTP/1.1
Host: d.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Alternative Usage Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example of using the Alternative instance for choice.

```Haskell
method = string "GET" <|> string "POST" <|> string "PUT"
```

--------------------------------

### Example HTTP Request 2

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Another sample HTTP GET request for an image, with similar headers.

```http
GET /S-IpsJrOKuaK9GZ8.jpg HTTP/1.1
Host: c.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Example HTTP Request 13

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /aNd2zNRLXiMnKUFh.jpg HTTP/1.1
Host: c.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### GET Request for Favicon

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A GET request for the favicon.

```http
GET /favicon.ico HTTP/1.1
Host: www.redditstatic.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
```

--------------------------------

### Example HTTP Request 11

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /rnWf8CjBcyPQs5y_.jpg HTTP/1.1
Host: f.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Example HTTP Request 15

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for a PNG file.

```http
GET /sprite-reddit.an0Lnf61Ap4.png HTTP/1.1
Host: www.redditstatic.com
```

--------------------------------

### Example HTTP Request 1

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image, including headers.

```http
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/

GET /eMWMpmm9APNeNqcF.jpg HTTP/1.1
Host: e.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### atEnd Parser Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example of using the atEnd parser.

```Haskell
string "END" >> atEnd  -- Match END at end
```

--------------------------------

### Testing Patterns

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/usage-examples.md

Demonstrates how to test Attoparsec parsers using QuickCheck for property-based and roundtrip testing, and provides an example for performance testing.

```haskell
import Test.QuickCheck
import Test.Hspec

-- Property-based testing
spec = describe "Parser" $ do
  it "parses positive integers" $ 
    parseOnly decimal "123" `shouldBe` Right (123 :: Int)
  
  it "fails on empty input" $ 
    isLeft (parseOnly decimal "")
  
  it "leaves non-digits" $ 
    parseOnly decimal "123abc" `shouldBe` Right (123 :: Int)

-- Roundtrip testing
prop_roundtrip x = 
  parseOnly parser (serialize x) == Right x

-- Performance testing
bench :: Int -> IO ()
bench n = do
  let input = BS.replicate n '1'
  let start = getCPUTime
  parseOnly (many digit) input
  let elapsed = getCPUTime - start
  putStrLn $ "Parsed " ++ show n ++ " digits in " ++ show elapsed ++ "ms"

```

--------------------------------

### Example HTTP Request 3

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /3V6dj9PDsNnheDXn.jpg HTTP/1.1
Host: c.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Dropbox Notification Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

An example of an HTTP GET request for Dropbox notifications.

```http
GET /subscribe?host_int=1042356184&ns_map=571794054_374233948806,464381511_13349283399&user_id=245722467&nid=1399334269710011966&ts=1400862514 HTTP/1.1
Host: notify8.dropbox.com
Accept-Encoding: identity
Connection: keep-alive
X-Dropbox-Locale: en_US
User-Agent: DropboxDesktopClient/2.7.54 (Macintosh; 10.8; ('i32',); en_US)
```

--------------------------------

### Adzerk Advertiser Image Request (ads-load.html referer)

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET request to static.adzerk.net for an advertiser image, with a different referer.

```http
GET /Advertisers/63cfd0044ffd49c0a71a6626f7a1d8f0.jpg HTTP/1.1
Host: static.adzerk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads-load.html?bust2
```

--------------------------------

### Example HTTP Request 6

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /nGsQj15VyOHMwmq8.jpg HTTP/1.1
Host: c.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Example HTTP Request 9

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /WJFFPxD8X4JO_lIG.jpg HTTP/1.1
Host: f.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Adzerk Advertiser Image Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET request to static.adzerk.net for an advertiser image.

```http
GET /Advertisers/a774d7d6148046efa89403a8db635a81.jpg HTTP/1.1
Host: static.adzerk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads.html?sr=-reddit.com&bust2
```

--------------------------------

### GET Request for Image File

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A GET request for an image file, including a Referer header.

```http
GET /kill.png HTTP/1.1
Host: www.redditstatic.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Example HTTP Request 8

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /L5e1HcZLv1iu4nrG.jpg HTTP/1.1
Host: f.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Adzerk Static Asset Requests

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET requests to static.adzrk.net for JavaScript and CSS files.

```http
GET /Extensions/adFeedback.js HTTP/1.1
Host: static.adzrk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: */*
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads.html?sr=-reddit.com&bust2
```

```http
GET /Extensions/adFeedback.css HTTP/1.1
Host: static.adzrk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: text/css,*/*;q=0.1
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads.html?sr=-reddit.com&bust2
```

--------------------------------

### Parsing Configuration Files

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/usage-examples.md

Parses a simple key-value configuration file format, ignoring comments and blank lines.

```haskell
#{-# LANGUAGE OverloadedStrings #-}
import Data.Attoparsec.Text
import qualified Data.Text as T
import qualified Data.Text.IO as TIO
import Data.Map (Map)
import qualified Data.Map as Map

type Config = Map String String

-- Configuration file format: key = value
configLine = do
  skipSpace
  key <- takeWhile1 (/= '=')
  skipSpace
  char '='
  skipSpace
  value <- takeTill (\c -> c == '\n')
  skipSpace
  return (T.unpack key, T.unpack value)

-- Skip comments and blank lines
comment = skipSpace *> char '#' *> manyTill anyChar endOfLine *> pure ()
blank = skipSpace *> endOfLine *> pure ()

-- Configuration file
configFile = do
  skipSpace
  items <- many (try comment <|> try blank <|> configLine)
  return $ Map.fromList items

-- Usage
loadConfig :: FilePath -> IO (Either String Config)
loadConfig path = do
  content <- TIO.readFile path
  return $ parseOnly configFile content

-- Example config file:
-- # Comment
-- debug = true
-- port = 8080
-- host = localhost

```

--------------------------------

### takeWhile Parser Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example of using the takeWhile parser.

```Haskell
takeWhile (\w -> w /= 10)  -- Until newline
```

--------------------------------

### eitherResult Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/errors.md

An example demonstrating the use of `eitherResult`.

```haskell
case eitherResult (parse myParser input) of
  Right val -> processValue val
  Left err -> handleError err
```

--------------------------------

### Example HTTP Request 4

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for an image.

```http
GET /wQ3-VmNXhv8sg4SJ.jpg HTTP/1.1
Host: c.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### GET Request for CSS File

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A GET request for a CSS file, including a Referer header.

```http
GET /reddit.v_EZwRzV-Ns.css HTTP/1.1
Host: www.redditstatic.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: text/css,*/*;q=0.1
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Reddit Ad Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

An example of an HTTP GET request for an ad from Reddit.

```http
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads-load.html?bust2
Cookie: S_9994987=6754579095859875029; A4=01fmFvgRnI09SF00000; u2=d1263d39-874b-4a89-86cd-a2ab0860ed4e3Zl040

GET /i.gif?e=eyJhdiI6NjIzNTcsImF0Ijo4LCJjbSI6MTE2MzUxLCJjaCI6Nzk4NCwiY3IiOjMzNzAxOCwiZGkiOiI3OTdlZjU3OWQ5NjE0ODdiODYyMGMyMGJkOTE4YzNiMSIsImRtIjoxLCJmYyI6NDE2MTMxLCJmbCI6MjEwNDY0LCJrdyI6Ii1yZWRkaXQuY29tIiwibWsiOiItcmVkZGl0LmNvbSIsIm53Ijo1MTQ2LCJwYyI6MCwicHIiOjIwMzYyLCJydCI6MSwicmYiOiJodHRwOi8vd3d3LnJlZGRpdC5jb20vIiwic3QiOjI0OTUwLCJ1ayI6InVlMS01ZWIwOGFlZWQ5YTc0MDFjOTE5NWNiOTMzZWI3Yzk2NiIsInRzIjoxNDAwODYyNTkzNjRmfQ&s=OjzxzXAgQksbdQOHNm-bjZcnZPA HTTP/1.1
Host: engine.adzerk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads-load.html?bust2
Cookie: azk=ue1-5eb08aeed9a7401c9195cb933eb7c966
```

--------------------------------

### Parsing with State

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/usage-examples.md

Shows how to incorporate state into parsers, such as tracking line and column numbers during parsing. This example uses IORef to manage mutable state within the parsing process.

```haskell
{-# LANGUAGE OverloadedStrings #-}
import Data.Attoparsec.Text
import Data.IORef
import Control.Monad (when)

-- Parse with state tracking
data ParserState = ParserState
  { lineNum :: Int
  , colNum :: Int
  } deriving Show

-- Track position during parsing
withState :: Parser a -> IO (Either String (a, ParserState))
withState parser = do
  stateRef <- newIORef (ParserState 1 1)
  
  let statefulParser = do
    let updateState c = do
          st <- readIORef stateRef
          let (line, col) = if c == '\n'
                then (lineNum st + 1, 1)
                else (lineNum st, colNum st + 1)
          writeIORef stateRef (ParserState line col)
    
    a <- parser
    st <- readIORef stateRef
    return (a, st)
  
  -- Parse and return with state
  return undefined  -- Simplified example
```

--------------------------------

### maybeResult Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/errors.md

An example demonstrating the use of `maybeResult`.

```haskell
maybeResult (parse myParser input) >>= print
```

--------------------------------

### Monadic Composition Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example of using monadic composition with Zepto.

```Haskell
parser = do
  _ <- string "GET "
  path <- takeWhile (/= 32)
  _ <- string " HTTP/"
  version <- take 3
  return (path, version)
```

--------------------------------

### GET Request for CSS File on Subdomain

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A GET request for a CSS file hosted on a thumbs.redditmedia.com subdomain.

```http
GET /rZ_rD5TjrJM0E9Aj.css HTTP/1.1
Host: e.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: text/css,*/*;q=0.1
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### string Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/bytestring-char8.md

Example of using string to match a specific prefix.

```Haskell
string "HTTP/"
```

--------------------------------

### GET Request for JavaScript File

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A GET request for a JavaScript file, including a Referer header.

```http
GET /reddit-init.en-us.O1zuMqOOQvY.js HTTP/1.1
Host: www.redditstatic.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: */*
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### parseT Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example usage of the parseT function.

```Haskell
result <- parseT myParser (BS.pack "data")
case result of
  Right val -> print val
  Left err -> putStrLn err
```

--------------------------------

### Running Parsers

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/quick-reference.md

Examples of how to run Attoparsec parsers with strict ByteString, strict Text, lazy ByteString, and Zepto.

```Haskell
-- Strict ByteString
parse parser input                      -- IResult
parseOnly parser input                  -- Either String
parseTest parser input                  -- Print to stdout
parseWith getInput parser initial      -- Monadic refill

-- Strict Text
parse parser input                      -- IResult
parseOnly parser input                  -- Either String

-- Lazy
parse parser lazyInput                  -- Result (no Partial)

-- Zepto
Zepto.parse parser input               -- Either String
```

--------------------------------

### HTTP Request Parsing

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

An example demonstrating how to parse a simple HTTP request using Zepto.

```haskell
import Data.Attoparsec.Zepto
import qualified Data.ByteString as BS

data HttpRequest = HttpRequest
  { method :: ByteString
  , path :: ByteString
  , version :: ByteString
  }
  deriving Show

httpRequest :: Parser HttpRequest
httpRequest = do
  m <- takeWhile (/= 32)          -- Method until space
  _ <- string " "
  p <- takeWhile (/= 32)          -- Path until space
  _ <- string " HTTP/"
  v <- take 3                     -- Version "1.1" etc
  return (HttpRequest m p v)

main = do
  let input = BS.pack "GET /index.html HTTP/1.1\r\n"
  case parse httpRequest input of
    Right req -> print req
    Left err -> putStrLn $ "Error: " ++ err
```

--------------------------------

### Adzerk HTML Load Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET request to static.adzerk.net for an HTML ad loading page.

```http
GET /reddit/ads-load.html?bust2 HTTP/1.1
Host: static.adzerk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Serving-Sys BurstingPipe Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET request to bs.serving-sys.com for ad server bursting pipe, likely for impression tracking.

```http
GET /BurstingPipe/adServer.bs?cn=tf&c=19&mc=imp&pli=9994987&PluID=0&ord=1400862593644&rtu=-1 HTTP/1.1
Host: bs.serving-sys.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads.html?sr=-reddit.com&bust2
```

```http
GET /BurstingPipe/adServer.bs?cn=tf&c=19&mc=imp&pli=9962555&PluID=0&ord=1400862593645&rtu=-1 HTTP/1.1
Host: bs.serving-sys.com
```

--------------------------------

### GET Request for JPG Image

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A GET request for a JPG image hosted on a thumbs.redditmedia.com subdomain.

```http
GET /AMZM4CWd6zstSC8y.jpg HTTP/1.1
Host: b.thumbs.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### Example HTTP Request 14

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

A sample HTTP GET request for a GIF file.

```http
GET /droparrowgray.gif HTTP/1.1
Host: www.redditstatic.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.redditstatic.com/reddit.v_EZwRzV-Ns.css
```

--------------------------------

### Custom Parser Combinators

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/usage-examples.md

Provides examples of custom parser combinators that can be built using Attoparsec's combinator library. This includes functions for counting items separated by a delimiter, left-associative chaining, and optional parsing with actions.

```haskell
-- Parse exactly N items separated by separator
countSepBy :: Int -> Parser a -> Parser s -> Parser [a]
countSepBy n p sep = go 0 []
  where
    go count acc
      | count >= n = return (reverse acc)
      | count == 0 = do
          a <- p
          go 1 (a:acc)
      | otherwise = do
          sep
          a <- p
          go (count + 1) (a:acc)

-- Chainl1 for left-associative operators
chainl1 :: Parser a -> Parser (a -> a -> a) -> Parser a
chainl1 p op = do
  a <- p
  rest a
  where
    rest a = do
      o <- op
      b <- p
      rest (o a b)
      <|> return a

-- Optional with action
optionally :: Parser a -> (a -> Parser b) -> Parser (Maybe b)
optionally p action = (Just <$> (p >>= action)) <|> return Nothing
```

--------------------------------

### MonadIO Usage Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/zepto.md

Example of performing I/O within a Zepto parser.

```Haskell
parser = do
  n <- take 4
  liftIO $ putStrLn ("Got " ++ show n)
  return n
```

--------------------------------

### eitherP Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/bytestring-parsing.md

Example usage of eitherP to parse either 'on' or 'off'.

```Haskell
eitherP (string "on") (string "off")
```

--------------------------------

### Incremental Parsing Example with feed

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/errors.md

An example showing how to use `feed` for incremental parsing with a list of ByteStrings.

```haskell
parseIncremental :: Parser a -> [ByteString] -> Either String a
parseIncremental parser inputs = go (parse parser "")
  where
    go (Done _ a) = Right a
    go (Fail _ _ msg) = Left msg
    go (Partial k) = case inputs of
      [] -> go (feed (Partial k) "")  -- Signal EOF
      (x:xs) -> go (feed (Partial k) x)
```

--------------------------------

### parseOnly Function Examples

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/text-parsing.md

Examples demonstrating the behavior of parseOnly.

```Haskell
parseOnly letter "A"  -- Right 'A'
parseOnly digit "x"   -- Left "not a digit"
```

--------------------------------

### Parsing Log Files

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/usage-examples.md

Parses log entries with timestamps, levels, and messages.

```haskell
#{-# LANGUAGE OverloadedStrings #-}
import Data.Attoparsec.ByteString.Char8
import qualified Data.ByteString as BS
import Data.Time (UTCTime)
import Data.Time.Format (parseTimeOrError, defaultTimeLocale)

data LogEntry = LogEntry
  { timestamp :: String
  , level :: String
  , message :: String
  } deriving Show

-- ISO 8601 timestamp
timestamp = count 19 anyChar  -- "2024-05-27T12:34:56"

-- Log level
logLevel = "DEBUG" <|> "INFO" <|> "WARN" <|> "ERROR"

-- Log entry
logEntry = do
  ts <- timestamp
  skipSpace
  char '['
  lv <- logLevel
  char ']'
  skipSpace
  msg <- takeTill (\c -> c == '\n')
  endOfLine
  return LogEntry { timestamp = ts, level = lv, message = msg }

-- Multiple entries
logFile = many logEntry

-- Usage
parseLogFile :: FilePath -> IO (Either String [LogEntry])
parseLogFile path = do
  content <- BS.readFile path
  return $ parseOnly logFile content

```

--------------------------------

### Incremental Parsing

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/usage-examples.md

Demonstrates how to parse input incrementally, which is useful for handling large inputs or network streams. It shows a parser that works on chunks of ByteString and how to signal the end of input.

```haskell
{-# LANGUAGE OverloadedStrings #-}
import Data.Attoparsec.ByteString
import qualified Data.ByteString as BS
import Control.Monad (forever)

-- Parser that works incrementally
myParser = many (decimal :: Parser Int) <* endOfInput

-- Feed input incrementally
parseIncrementally :: Parser a -> [BS.ByteString] -> Either String a
parseIncrementally parser chunks = go (parse parser "")
  where
    go (Done _ a) = Right a
    go (Fail _ ctx msg) = Left msg
    go (Partial k) = case chunks of
      [] -> go (feed (Partial k) "")  -- Signal EOF
      (x:xs) -> go (feed (Partial k) x)

-- Usage with network socket
parseStream socket parser = go (parse parser "")
  where
    go (Done rest a) = return a
    go (Fail _ _ msg) = fail msg
    go (Partial k) = do
      chunk <- BS.hGetSome socket 4096
      if BS.null chunk
        then go (feed (Partial k) "")  -- EOF
        else go (feed (Partial k) chunk)
```

--------------------------------

### Reddit Pixel Tracking Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET request to pixel.redditmedia.com for tracking pixel.

```http
GET /pixel/of_doom.png?id=t3_25jzeq-t8_k2ii&hash=da31d967485cdbd459ce1e9a5dde279fef7fc381&r=1738649500 HTTP/1.1
Host: pixel.redditmedia.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://www.reddit.com/
```

--------------------------------

### match Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/bytestring-parsing.md

Example usage of match to return consumed bytes and parse result.

```Haskell
match (many1 digit)  -- Returns ("123", [49,50,51])
```

--------------------------------

### Incremental Input

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/quick-reference.md

An example of how to handle incremental parsing with Attoparsec.

```Haskell
parseIncremental p input = go (parse p input)
  where
    go (Done rest a) = Right a
    go (Fail _ _ msg) = Left msg
    go (Partial k) = go (k "")  -- Signal EOF
```

--------------------------------

### Adzerk Engine Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET request to Adzerk's engine.adzerk.net for ad serving.

```http
GET /ados?t=1400862512892&request={%22Placements%22:[{%22A%22:5146,%22S%22:24950,%22D%22:%22main%22,%22AT%22:5},{%22A%22:5146,%22S%22:24950,%22D%22:%22sponsorship%22,%22AT%22:8}],%22Keywords%22:%22-reddit.com%22,%22Referrer%22:%22http%3A%2F%2Fwww.reddit.com%2F%22,%22IsAsync%22:true,%22WriteResults%22:true} HTTP/1.1
Host: engine.adzerk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: */*
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads.html?sr=-reddit.com&bust2
```

--------------------------------

### parseOnly Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/errors.md

An example demonstrating how to use `parseOnly` and handle its `Either` result.

```haskell
case parseOnly decimal "123" of
  Right n -> print n
  Left err -> putStrLn $ "Parse error: " ++ err
```

--------------------------------

### Adzerk Tracker Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET request to Adzerk's secure.adzerk.net for tracking information.

```http
GET /fetch-trackers?callback=jQuery111005268222517967478_1400862512407&ids%5B%5D=t3_25jzeq-t8_k2ii&_=1400862512408 HTTP/1.1
Host: secure.adzerk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: */*
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads.html?sr=-reddit.com&bust2
```

--------------------------------

### Alternative Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/combinators.md

Example of using the alternative operator (<|>) to try the next parser if the first fails.

```haskell
-- Alternative: try next option
digit <|> letter
```

--------------------------------

### Adzerk Dynamic Image Request

Source: https://github.com/haskell/attoparsec/blob/master/examples/http-requests.txt

Example HTTP GET request to engine.adzerk.net for a dynamically generated image, likely for tracking or reporting.

```http
GET /i.gif?e=eyJhdiI6NjIzNTcsImF0Ijo1LCJjbSI6MTE2MzUxLCJjaCI6Nzk4NCwiY3IiOjMzNzAxNSwiZGkiOiI4NmI2Y2UzYWM5NDM0MjhkOTk2ZTg4MjYwZDE5ZTE1YyIsImRtIjoxLCJmYyI6NDE2MTI4LCJmbCI6MjEwNDY0LCJrdyI6Ii1yZWRkaXQuY29tIiwibWsiOiItcmVkZGl0LmNvbSIsIm53Ijo1MTQ2LCJwYyI6MCwicHIiOjIwMzYyLCJydCI6MSwicmYiOiJodHRwOi8vd3d3LnJlZGRpdC5jb20vIiwic3QiOjI0OTUwLCJ1ayI6InVlMS01ZWIwOGFlZWQ5YTc0MDFjOTE5NWNiOTMzZWI3Yzk2NiIsInRzIjoxNDAwODYyNTkzNjQ1fQ&s=lwlbFf2Uywt7zVBFRj_qXXu7msY HTTP/1.1
Host: engine.adzerk.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:15.0) Gecko/20100101 Firefox/15.0.1
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://static.adzerk.net/reddit/ads.html?sr=-reddit.com&bust2
Cookie: azk=ue1-5eb08aeed9a7401c9195cb933eb7c966
```

--------------------------------

### Complete Input (Most Common)

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/quick-reference.md

Example of parsing a complete ByteString input using `parseOnly`.

```Haskell
import Data.Attoparsec.ByteString.Char8

case parseOnly myParser input of
  Right result -> process result
  Left err -> putStrLn err
```

--------------------------------

### Building Error Messages Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/errors.md

Illustrates how context stacks from inner to outer parsers when building error messages.

```haskell
parser = 
  (string "PREFIX" <?> "prefix") *>
  (many digit <?> "digits") <*
  (string "SUFFIX" <?> "suffix")

-- If fails on SUFFIX:
-- Context: ["suffix", "digits", "prefix"]
-- Formatted: "prefix > digits > suffix: string"
```

--------------------------------

### Parsing HTTP Requests

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/usage-examples.md

Parses a simplified HTTP request, including method, path, version, and headers.

```haskell
#{-# LANGUAGE OverloadedStrings #-}
import Data.Attoparsec.ByteString as P
import Data.Attoparsec.ByteString.Char8
import qualified Data.ByteString as BS
import Data.Word (Word8)

data HttpRequest = HttpRequest
  { method :: BS.ByteString
  , path :: BS.ByteString
  , version :: BS.ByteString
  , headers :: [(BS.ByteString, BS.ByteString)]
  } deriving Show

-- HTTP method
httpMethod = string "GET" <|> string "POST" <|> string "PUT" <|> string "DELETE"

-- HTTP version
httpVersion = string "HTTP/" >> takeWhile (/= '\r')

-- Request line
requestLine = do
  m <- httpMethod
  skipSpace
  p <- takeWhile (\c -> c /= ' ')
  skipSpace
  v <- httpVersion
  endOfLine
  return (m, p, v)

-- Header line
headerLine = do
  name <- takeWhile (\c -> c /= ':')
  char ':'
  skipSpace
  value <- takeTill (\c -> c == '\r' || c == '\n')
  endOfLine
  return (name, value)

-- Full request
httpRequest = do
  (m, p, v) <- requestLine
  hs <- many headerLine
  endOfLine
  return HttpRequest { method = m, path = p, version = v, headers = hs }

-- Usage
main = do
  input <- BS.readFile "request.txt"
  case parseOnly httpRequest input of
    Right req -> print req
    Left err -> putStrLn $ "Parse error: " ++ err

```

--------------------------------

### satisfy Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/bytestring-char8.md

Example of using satisfy to match digits.

```Haskell
satisfy isDigit  -- Matches '0'-'9'
```

--------------------------------

### satisfy Function Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/text-parsing.md

Example of using satisfy with a predicate.

```Haskell
satisfy isAlpha  -- Matches letters
```

--------------------------------

### skipMany Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/bytestring-parsing.md

Example usage of skipMany to skip all whitespace characters.

```Haskell
skipMany space  -- Skip all spaces
```

--------------------------------

### Apply Example

Source: https://github.com/haskell/attoparsec/blob/master/_autodocs/api-reference/combinators.md

Example of using the apply operator (<*>) for function application within parsers.

```haskell
-- Apply: function application in parser
(+) <$> decimal <*> (char '+' *> decimal)
```