View source for No import of Prelude

== Question ==

Is it possible to not load the Prelude when compiling a Haskell module?

== Answer ==

You can either do

<haskell>
import Prelude()
</haskell>

or add
<haskell>
{-# LANGUAGE NoImplicitPrelude #-}
</haskell>
to the top of the module, or equivalently compile with <code>-XNoImplicitPrelude</code> (or older <code>-fno-implicit-prelude</code>) option.

<hask>import Prelude()</hask> is less aggressive than <code>NoImplicitPrelude</code>.
E.g. with the first method some functions are imported which are silently inserted for several syntactic constructs.
A bare untyped integral number is rewritten as <hask>fromIntegral num</hask>
(so its type will be <hask>Num a => a</hask>),
and list generation syntax is rewritten as follows:
<hask>[n..]</hask> <math>\rightarrow</math> <hask>enumFrom</hask>,
<hask>[n..m]</hask> <math>\rightarrow</math> <hask>enumFromTo</hask>,
<hask>[n,o..]</hask> <math>\rightarrow</math> <hask>enumFromThen</hask>,
<hask>[n,o..m]</hask> <math>\rightarrow</math> <hask>enumFromThenTo</hask>.

There are some such for which even <code>-fno-implicit-prelude</code> isn't enough;
I think these are documented in the "bugs" section of the GHC manual.

== See also ==

* Haskell-Cafe: [http://www.haskell.org/pipermail/haskell-cafe/2008-January/037839.html Not to load Prelude]

[[Category:FAQ]]