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# REPL
The REPL lets you interact with Elm values and functions in your terminal.
## Use
You can type in expressions, definitions, custom types, and module imports using normal Elm syntax.
```elm
> 1 + 1
2 : number
> "hello" ++ "world"
"helloworld" : String
```
The same can be done with definitions and custom types:
```elm
> fortyTwo = 42
42 : number
> increment n = n + 1
<function> : number -> number
> increment 41
42 : number
> factorial n =
| if n < 1 then
| 1
| else
| n * factorial (n-1)
|
<function> : number -> number
> factorial 5
120 : number
> type User
| = Regular String
| | Visitor String
|
> case Regular "Tom" of
| Regular name -> "Hey again!"
| Visitor name -> "Nice to meet you!"
|
"Hey again!" : String
```
When you run `elm repl` in a project with an [`elm.json`](https://github.com/elm/compiler/blob/master/docs/elm.json/application.md) file, you can import any module available in the project. So if your project has an `elm/html` dependency, you could say:
```elm
> import Html exposing (Html)
> Html.text "hello"
<internals> : Html msg
> Html.text
<function> : String -> Html msg
```
If you create a module in your project named `MyThing` in your project, you can say `import MyThing` in the REPL as well. Any module that is accessible in your project should be accessible in the REPL.
## Exit
To exit the REPL, you can type `:exit`.
You can also press `ctrl-d` or `ctrl-c` on some platforms.
|
