# Upgrading packages/Updating to GHC 6.10

### From HaskellWiki

A list of things that need updating when porting packages to newer library/cabal versions.

If you maintain a Haskell package this is for you. For older versions of this document:

**Updating to GHC 6.10 and Cabal 1.6**

When upgrading to GHC 6.10, any of your packages that worked against the base-3 library will continue to work. GHC 6.10 provides both the old base-3 library and the new base-4.

To ensure your old code continues to work, you can have the code compile and link against base-3, and then, over time, migrate code to the base-4 series.

## Contents |

## 1 Adding base-3 constraints

How to do this depends on how you build your Haskell code. We'll start with the most simplistic build mechanisms. cabal-install, the most sophisticated tool, will sort this all out for you anyway, so things should change.

### 1.1 ghc --make

Force use of package base-3 when using --make,

ghc --make --package base-3.0.3.0

### 1.2 runhaskell

If you build your packages with the 'runhaskell Setup.hs configure' method, then you can force the use of base-3,

--constraint="base<4"

### 1.3 cabal-install

No change required. Should it be necessary to override, use

--constraint="base<4"

## 2 Changes in base 4

- Exceptions