Every Elm project needs the core libraries. They provide basic functionality including:

• Basic operations like addition and subtraction
• Core data structures like lists, dictionaries, and sets
• Underlying implementation of Signals
• Core rendering libraries

In all Elm files there is a small set of default imports:

import Basics exposing (..)
import List exposing ( List, (::) )
import Maybe exposing ( Maybe( Just, Nothing ) )
import Result exposing ( Result( Ok, Err ) )
import Signal exposing ( Signal )

The intention is to include things that are both extremely useful and very unlikely to overlap with anything that anyone will ever write in a library. By keeping the set of default imports small, it also becomes easier to use whatever version of map suits your fancy. Finally, it makes it easier to figure out where the heck a function is coming from.