No import of Prelude

(Difference between revisions)

Revision as of 02:49, 4 December 2010

Is it possible to not load the Prelude module 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 -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 not to load Prelude module when compiling a Haskell module?
+Is it possible to not load the Prelude module when compiling a Haskell module?
 == Answer ==