Haskell – Fully featured CSV parser for Haskell

csvhaskell

Can anybody recommend a way to parse CSV files with options to:

set cells/fields separator
set end of record/row terminator
set quote-character for fields
support of UTF-8 strings
ability to write in-memory CSV structure back to a file

I did try Text.CSV but it's very simple and lacks most of the above features.
Is there some more advanced CSV parsing module or do I have to write it "from scratch" i.e. using Text.ParserCombinators? I do not intend to reinvent a wheel.

Take care.

Best Answer

I can't recommend a ready-to-go, packaged-up CSV parser for Haskell, but I remember that the book Real-World Haskell by Bryan O'Sullivan et al. contains a chapter on Parsec, which the authors demonstrate by creating a CSV parser.

The relevant chapter 16: Using Parsec is available online; check the section titled Extended Example: Full CSV Parser.

Related Solutions

Mysql – How to output MySQL query results in CSV format

From Save MySQL query results into a text or CSV file:

SELECT order_id,product_name,qty
FROM orders
WHERE foo = 'bar'
INTO OUTFILE '/var/lib/mysql-files/orders.csv'
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n';

Note: That syntax may need to be reordered to

SELECT order_id,product_name,qty
INTO OUTFILE '/var/lib/mysql-files/orders.csv'
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
FROM orders
WHERE foo = 'bar';

in more recent versions of MySQL.

Using this command, columns names will not be exported.

Also note that /var/lib/mysql-files/orders.csv will be on the server that is running MySQL. The user that the MySQL process is running under must have permissions to write to the directory chosen, or the command will fail.

If you want to write output to your local machine from a remote server (especially a hosted or virtualize machine such as Heroku or Amazon RDS), this solution is not suitable.

Dealing with commas in a CSV file

There's actually a spec for CSV format, RFC 4180 and how to handle commas:

Fields containing line breaks (CRLF), double quotes, and commas should be enclosed in double-quotes.

^{http://tools.ietf.org/html/rfc4180}

So, to have values foo and bar,baz, you do this:

foo,"bar,baz"

Another important requirement to consider (also from the spec):

If double-quotes are used to enclose fields, then a double-quote appearing inside a field must be escaped by preceding it with another double quote. For example:
"aaa","b""bb","ccc"

Best Answer

Related Solutions

Mysql – How to output MySQL query results in CSV format

Dealing with commas in a CSV file

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