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A fast Haskell library for rendering common Haskell datatypes in text form.
Branch: master

Fix build

latest commit 9748b60d7e
@bos authored


Welcome to blaze-textual

blaze-textual is a fast Haskell library for rendering common Haskell datatypes in text form using the blaze-builder library.

Important note for users of GHCi and Template Haskell

To achieve excellent performance for rendering floating point numbers, this package can optionally use the double-conversion package.

Unfortunately, due to bugs in GHC, some uses of GHCi and Template Haskell can crash if the double-conversion package is used. As a result, this package's use of double-conversion is disabled by default.

If you enable use of double-conversion and are affected by these problems, you should expect the 5289 crash to look like this:

Loading package double-conversion- ... can't load .so/.DLL for: stdc++

The 5386 crash causes GHCi to die with a floating point exception (SIGFPE).

To work around these bugs, this package includes an alternative, slower, floating point conversion that is written in pure Haskell. Although it is 10 times slower than the double-conversion package, it is the default because it does not crash.

If you don't use GHCi or Template Haskell, and you want to force the use of double-conversion, you can reinstall this package by disabling the native flag with cabal:

cabal install -f-native --reinstall

Afterwards, you will also need to reinstall any downstream packages that depend on this one, e.g. the aeson JSON library:

cabal install aeson --reinstall

Join in!

We are happy to receive bug reports, fixes, documentation enhancements, and other improvements.

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 git or Mercurial.)


This library is written and maintained by Bryan O'Sullivan,

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