# elm-syntax

Elm Syntax in Elm: for parsing and writing Elm in Elm.

## How does this work?

When Elm code is parsed, it's converted into an Abstract Syntax Tree (AST).
The AST lets us represent the code in a way that's much easier to work with when programming.

Here's an example of that:
Code: `3 + 4 * 2`
AST:
```elm
OperatorApplication
    (Integer 3)
    "+"
    (OperatorApplication
        (Integer 4)
        "*"
        (Integer 2)
    )
```

Notice how it forms a tree structure where we first multiply together 4 and 2, and then add the result with 3.
That's where the "tree" part of AST comes from.

## Getting Started

```elm
import Elm.Parser
import Html exposing (Html)

src : String
src =
    """module Foo exposing (foo)

foo = 1
"""

parse : String -> String
parse input =
    case Elm.Parser.parseToFile input of
        Err e ->
            "Failed: " ++ Debug.toString e

        Ok v ->
            "Success: " ++ Debug.toString v

main : Html msg
main =
    Html.text (parse src)
```

Used in:

* [`elm-review`](https://elm-review.com/)
* [`elm-codegen`](https://package.elm-lang.org/packages/mdgriffith/elm-codegen/latest/)
* [`elm-analyse`](https://github.com/stil4m/elm-analyse)
* [`elm-xref`](https://github.com/zwilias/elm-xref)
* [`elm-lens`](https://github.com/mbuscemi/elm-lens)