An efficient packed, immutable Unicode text type (both strict and lazy), with a powerful loop fusion optimization framework. The Text type represents Unicode character strings, in a time and space-efficient manner. This package provides text processing capabilities that are optimized for performance critical use, both in terms of large data quantities and high speed. The Text type provides character-encoding, type-safe case conversion via whole-string case conversion functions (see Data.Text). It also provides a range of functions for converting Text values to and from ByteStrings, using several standard encodings (see Data.Text.Encoding). Efficient locale-sensitive support for text IO is also supported (see Data.Text.IO). These modules are intended to be imported qualified, to avoid name clashes with Prelude functions, e.g. To use an extended and very rich family of functions for working with Unicode text (including normalization, regular expressions, non-standard encodings, text breaking, and locales), see the text-icu package based on the well-respected and liberally licensed ICU library. Currently the text library uses UTF-16 as its internal representation which is neither a fixed-width nor always the most dense representation for Unicode text. We're currently investigating the feasibility of changing Text's internal representation to UTF-8 and if you need such a Text type right now you might be interested in using the spin-off packages text-utf8 and text-short.

data, library, text, Propose Tags , Data.Text, Data.Text.Array, Data.Text.Encoding, Data.Text.Encoding.Error, Data.Text.Foreign, Data.Text.IO, Data.Text.Internal, Data.Text.Internal.Builder, Data.Text.Internal.Builder.Functions, Data.Text.Internal.Builder.Int.Digits, Data.Text.Internal.Builder.RealFloat.Functions, Data.Text.Internal.Encoding.Fusion, Data.Text.Internal.Encoding.Fusion.Common, Data.Text.Internal.Encoding.Utf16, Data.Text.Internal.Encoding.Utf32, Data.Text.Internal.Encoding.Utf8, Data.Text.Internal.Functions, Data.Text.Internal.Fusion, Data.Text.Internal.Fusion.CaseMapping, Data.Text.Internal.Fusion.Common, Data.Text.Internal.Fusion.Size, Data.Text.Internal.Fusion.Types, Data.Text.Internal.IO, Data.Text.Internal.Lazy, Data.Text.Internal.Lazy.Encoding.Fusion, Data.Text.Internal.Lazy.Fusion, Data.Text.Internal.Lazy.Search, Data.Text.Internal.Private, Data.Text.Internal.Read, Data.Text.Internal.Search, Data.Text.Internal.Unsafe, Data.Text.Internal.Unsafe.Char, Data.Text.Internal.Unsafe.Shift, Data.Text.Lazy, Data.Text.Lazy.Builder, Data.Text.Lazy.Builder.Int, Data.Text.Lazy.Builder.RealFloat, Data.Text.Lazy.Encoding, Data.Text.Lazy.IO, Data.Text.Lazy.Internal, Data.Text.Lazy.Read, Data.Text.Read, Data.Text.Unsafe, package description on Hackage, github issue tracker, git repository, Mercurial mirror,, haskell, string-manipulation, unicode
cabal install text-


text: Fast, packed Unicode strings, using stream fusion

This package provides the Data.Text library, a library for the space- and time-efficient manipulation of Unicode text in Haskell.

Please refer to the package description on Hackage for more information.

Get involved!

Please report bugs via the github issue tracker.

Master git repository:

  • git clone git://

There's also a Mercurial mirror:

  • hg clone

(You can create and contribute changes using either Mercurial or git.)


The base code for this library was originally written by Tom Harper, based on the stream fusion framework developed by Roman Leshchinskiy, Duncan Coutts, and Don Stewart.

The core library was fleshed out, debugged, and tested by Bryan O'Sullivan, and he is the current maintainer.