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No import of Prelude

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1 Question

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

2 Answer

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.

3 See also