Safe Haskell	None

System.IO.Streams.Csv

Contents

Decoding CSV
Encoding CSV

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

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
Typeable StreamDecodingError
Exception StreamDecodingError

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.