Prelude

A Prelude module replacement.

This package provides a Prelude module drop-in replacement for base's Prelude module.

Goals of this package include:

• Be reasonably modest and remain close in spirit to the base package's scope

• Depend only on base (via base-noprelude) for recent GHC versions

• Avoid partial functions being in scope by default; redefine common partial functions such as read or head to be Maybe-valued

• Provide a uniform Prelude across multiple GHC releases (currently GHC 7.0 and newer supported) to the extent possible given typeclass restructurings such as AMP or FTP

• Reduce import clutter by reexporting common verbs from modules such as Control.Monad and Control.Applicative

Versioning and Usage

This package is intended to be used in combination with base-noprelude and possibly base-orphans. Prelude strives to be faithful to the PVP; however, for technical reasons Prelude's API is not fully determined by its version due to changes in core typeclasses and consequently it's strongly advised to declare a dependency on Prelude always in conjunction with a dependency on base-noprelude.

For instance, all you need to do in order to use this package if you were previously depending on base via

build-depends:
    base (>= 4.3.0.0 && < 4.11) || ^>= 4.11.0.0

is to replace base by base-noprelude and also add a dependency on Prelude like so

build-depends:
    Prelude ^>= 0.1.0.0
  , base-noprelude (>= 4.3.0.0 && < 4.11) || ^>= 4.11.0.0

and this will effectively replace the implicit Prelude module.

Alternatively, if you only intend to support GHC 7.10 and newer, you can make use mixins like so

build-depends:
    Prelude ^>= 0.1.0.0
  , base (>= 4.8.0.0 && < 4.12) || ^>= 4.12.0.0

mixins: base hiding (Prelude)