Safe Haskell	None
Language	Haskell2010

System.IO.Streams.Csv

Contents

Decoding CSV
Encoding CSV
Convenience Exports

Description

This module exports functions which can be used to read instances of the cassava classes FromRecord and FromNamedRecord from an io-streams InputStream ByteString.

It also exports functions which can write instances of ToRecord and ToNamedRecord to an io-streams OutputStream ByteString.

See the System.IO.Streams.Csv.Tutorial module for a simple tutorial.

Synopsis

data StreamDecodingError = StreamDecodingError String
decodeStream :: FromRecord a => HasHeader -> InputStream ByteString -> IO (InputStream (Either String a))
decodeStreamWith :: FromRecord a => DecodeOptions -> HasHeader -> InputStream ByteString -> IO (InputStream (Either String a))
decodeStreamByName :: FromNamedRecord a => InputStream ByteString -> IO (InputStream (Either String a))
decodeStreamByNameWith :: FromNamedRecord a => DecodeOptions -> InputStream ByteString -> IO (InputStream (Either String a))
onlyValidRecords :: InputStream (Either String a) -> IO (InputStream a)
encodeStream :: ToRecord a => OutputStream ByteString -> IO (OutputStream a)
encodeStreamWith :: ToRecord a => EncodeOptions -> OutputStream ByteString -> IO (OutputStream a)
encodeStreamByName :: ToNamedRecord a => Header -> OutputStream ByteString -> IO (OutputStream a)
encodeStreamByNameWith :: ToNamedRecord a => EncodeOptions -> Header -> OutputStream ByteString -> IO (OutputStream a)
defaultEncodeOptions :: EncodeOptions
data Quoting
- = QuoteNone
- | QuoteMinimal
- | QuoteAll
data EncodeOptions = EncodeOptions {
- encDelimiter :: !Word8
- encUseCrLf :: !Bool
- encIncludeHeader :: !Bool
- encQuoting :: !Quoting
}
defaultDecodeOptions :: DecodeOptions
data DecodeOptions = DecodeOptions {
- decDelimiter :: !Word8
}
data HasHeader
- = HasHeader
- | NoHeader

Decoding CSV

These functions convert an io-streams InputStream ByteString stream into one that decodes CSV records and produces these decoded records.

Each of the decoding functions produce an InputStream which yields an Either value. Left String represents a record which failed type conversion. Right a is a successfully decoded record.

See the tutorial in System.IO.Streams.Csv.Tutorial for details on how to use the onlyValidRecords function to transform the decoding streams so that they only produce valid records and throw exceptions for bad records.

data StreamDecodingError Source #

Exception thrown when stream decoding cannot continue due to an error.

Constructors

StreamDecodingError String

Instances

Show StreamDecodingError Source #
Instance details Defined in System.IO.Streams.Csv.Decode Methods showsPrec :: Int -> StreamDecodingError -> ShowS # show :: StreamDecodingError -> String # showList :: [StreamDecodingError] -> ShowS #
Exception StreamDecodingError Source #
Instance details Defined in System.IO.Streams.Csv.Decode Methods toException :: StreamDecodingError -> SomeException # fromException :: SomeException -> Maybe StreamDecodingError # displayException :: StreamDecodingError -> String #

decodeStream Source #

Arguments

:: FromRecord a
=> HasHeader	Whether to skip a header or not.
-> InputStream ByteString	Upstream.
-> IO (InputStream (Either String a))	An `InputStream` which produces records.

Create an InputStream which decodes CSV records from the given upstream data source.

Equivalent to decodeStreamWith defaultDecodeOptions.

decodeStreamWith Source #

Arguments

:: FromRecord a
=> DecodeOptions	CSV decoding options.
-> HasHeader	Whether to skip a header or not.
-> InputStream ByteString	Upstream.
-> IO (InputStream (Either String a))	An `InputStream` which produces records.

Create an InputStream which decodes CSV records from the given upstream data source.

decodeStreamByName Source #

Arguments

:: FromNamedRecord a
=> InputStream ByteString	Upstream.
-> IO (InputStream (Either String a))	An `InputStream` which produces records.

Create an InputStream which decodes CSV records from the given upstream data source. Data should be preceded by a header.

Equivalent to decodeStreamByNameWith defaultDecodeOptions.

decodeStreamByNameWith Source #

Arguments

:: FromNamedRecord a
=> DecodeOptions	CSV decoding options.
-> InputStream ByteString	Upstream.
-> IO (InputStream (Either String a))	An `InputStream` which produces records.

Create an InputStream which decodes CSV records from the given upstream data source. Data should be preceded by a header.

onlyValidRecords Source #

Arguments

:: InputStream (Either String a)	Upstream.
-> IO (InputStream a)	An `InputStream` which only produces valid records.

Creates a new InputStream which only sends valid CSV records downstream. The first invalid record will throw an exception.

Encoding CSV

These functions convert an io-streams OutputStream ByteString stream into one that encodes records into CSV format before sending them downstream.

encodeStream Source #

Arguments

:: ToRecord a
=> OutputStream ByteString	Downstream.
-> IO (OutputStream a)	New `OutputStream`.

Create a new OutputStream that can be fed ToRecord values which are converted to CSV. The records are encoded into ByteStrings and passed on to the given downstream OutputStream.

Equivalent to encodeStreamWith defaultEncodeOptions.

encodeStreamWith Source #

Arguments

:: ToRecord a
=> EncodeOptions	Encoding options.
-> OutputStream ByteString	Downstream.
-> IO (OutputStream a)	New `OutputStream`.

Create a new OutputStream that can be fed ToRecord values which are converted to CSV. The records are encoded into ByteStrings and passed on to the given downstream OutputStream.

encodeStreamByName Source #

Arguments

:: ToNamedRecord a
=> Header	CSV Header.
-> OutputStream ByteString	Downstream.
-> IO (OutputStream a)	New `OutputStream`.

Create a new OutputStream which can be fed ToNamedRecord values that will be converted into CSV. The records are encoded into ByteStrings and passed on to the given downstream OutputStream.

Equivalent to encodeStreamByNameWith defaultEncodeOptions.

encodeStreamByNameWith Source #

Arguments

:: ToNamedRecord a
=> EncodeOptions	Encoding options.
-> Header	CSV Header.
-> OutputStream ByteString	Downstream.
-> IO (OutputStream a)	New `OutputStream`.

Create a new OutputStream which can be fed ToNamedRecord values that will be converted into CSV. The records are encoded into ByteStrings and passed on to the given downstream OutputStream.

Convenience Exports

Export data types from Data.Csv

defaultEncodeOptions :: EncodeOptions #

Encoding options for CSV files.

data Quoting #

Should quoting be applied to fields, and at which level?

Constructors

QuoteNone	No quotes.
QuoteMinimal	Quotes according to RFC 4180.
QuoteAll	Always quote.

Instances

Eq Quoting
Instance details Defined in Data.Csv.Encoding Methods (==) :: Quoting -> Quoting -> Bool # (/=) :: Quoting -> Quoting -> Bool #
Show Quoting
Instance details Defined in Data.Csv.Encoding Methods showsPrec :: Int -> Quoting -> ShowS # show :: Quoting -> String # showList :: [Quoting] -> ShowS #

data EncodeOptions #

Options that controls how data is encoded. These options can be used to e.g. encode data in a tab-separated format instead of in a comma-separated format.

To avoid having your program stop compiling when new fields are added to EncodeOptions, create option records by overriding values in defaultEncodeOptions. Example:

myOptions = defaultEncodeOptions {
      encDelimiter = fromIntegral (ord '\t')
    }

N.B. The encDelimiter must not be the quote character (i.e. ") or one of the record separator characters (i.e. \n or \r).

Constructors

EncodeOptions
Fields encDelimiter :: !Word8 Field delimiter. encUseCrLf :: !Bool Record separator selection. `True` for CRLF (`\r\n`) and `False` for LF (`\n`). encIncludeHeader :: !Bool Include a header row when encoding `ToNamedRecord` instances. encQuoting :: !Quoting What kind of quoting should be applied to text fields.

Instances

Eq EncodeOptions
Instance details Defined in Data.Csv.Encoding Methods (==) :: EncodeOptions -> EncodeOptions -> Bool # (/=) :: EncodeOptions -> EncodeOptions -> Bool #
Show EncodeOptions
Instance details Defined in Data.Csv.Encoding Methods showsPrec :: Int -> EncodeOptions -> ShowS # show :: EncodeOptions -> String # showList :: [EncodeOptions] -> ShowS #

defaultDecodeOptions :: DecodeOptions #

Decoding options for parsing CSV files.

data DecodeOptions #

Options that controls how data is decoded. These options can be used to e.g. decode tab-separated data instead of comma-separated data.

To avoid having your program stop compiling when new fields are added to DecodeOptions, create option records by overriding values in defaultDecodeOptions. Example:

myOptions = defaultDecodeOptions {
      decDelimiter = fromIntegral (ord '\t')
    }

Constructors

DecodeOptions
Fields decDelimiter :: !Word8 Field delimiter.

Instances

Eq DecodeOptions
Instance details Defined in Data.Csv.Parser Methods (==) :: DecodeOptions -> DecodeOptions -> Bool # (/=) :: DecodeOptions -> DecodeOptions -> Bool #
Show DecodeOptions
Instance details Defined in Data.Csv.Parser Methods showsPrec :: Int -> DecodeOptions -> ShowS # show :: DecodeOptions -> String # showList :: [DecodeOptions] -> ShowS #

data HasHeader #

Is the CSV data preceded by a header?

Constructors

HasHeader	The CSV data is preceded by a header
NoHeader	The CSV data is not preceded by a header