No import of Prelude

(Difference between revisions)

Current revision

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

You can either do

import Prelude()

or add

{-# LANGUAGE NoImplicitPrelude #-}

to the top of the module, or equivalently compile with -XNoImplicitPrelude (or older -fno-implicit-prelude) option.

import Prelude()

is less aggressive than NoImplicitPrelude.

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

fromIntegral num

(so its type will be

Num a => a

and list generation syntax is rewritten as follows:

[n..]

$\rightarrow$

enumFrom

[n..m]

$\rightarrow$

enumFromTo

[n,o..]

$\rightarrow$

enumFromThen

[n,o..m]

$\rightarrow$

enumFromThenTo

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

@@ Line 1: / Line 1: @@
 == Question ==
-Is it possible to not load the Prelude module when compiling a Haskell module?
+Is it possible to not load the Prelude when compiling a Haskell module?
 == Answer ==
@@ Line 15: / Line 15: @@
 {-# LANGUAGE NoImplicitPrelude #-}
 </haskell>
-to the top of the module, or equivalently compile with <code>-fno-implicit-prelude</code> option.
+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>.
@@ Line 29: / Line 29: @@
 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 ==