Crate elm_ast 

A syn-quality Rust library for parsing and constructing Elm 0.19.1 ASTs.

elm-ast-rs provides a complete, strongly-typed representation of Elm source code as a Rust AST, along with a parser, pretty-printer, and visitor/fold traits for traversal and transformation.

Quick start

use elm_ast::{parse, print};

let source = r#"
module Main exposing (..)

add : Int -> Int -> Int
add x y =
    x + y
"#;

let module = parse(source).expect("valid Elm source parses");
assert_eq!(module.declarations.len(), 1);

let output = print(&module);
assert!(output.contains("add x y"));

Features

All features are enabled by default via full. Disable default-features and pick what you need to reduce compile times.

Feature	Description
full	Enables all features below (default)
parsing	parse() and parse_recovering() functions
printing	print(), Display impls, Printer struct
visit	Visit trait for immutable traversal
visit-mut	VisitMut for in-place mutation
fold	Fold for owned transformation
serde	Serialize/Deserialize on all AST types
wasm	WASM bindings via wasm-bindgen

AST overview

The root type is ElmModule, representing a complete .elm file. Every AST node is wrapped in Spanned<T>, which carries source location info (Span) alongside the value.

Key types: Expr, Pattern, TypeAnnotation, Declaration, Import, ModuleHeader.

Re-exports

pub use file::ElmModule;

pub use lexer::Lexer;

pub use node::Spanned;

pub use span::Position;

pub use span::Span;

pub use token::Token;

pub use parse::parse;

pub use parse::parse_recovering;

pub use print::pretty_print;

pub use print::pretty_print_converged;

pub use print::print;

Modules

builder

Builder helpers for constructing Elm AST nodes programmatically.

comment

declaration

display

Display implementations for AST types.

exposing

expr

file

fold

Owned transformation trait for rewriting Elm ASTs.

ident

import

lexer

literal

module_header

node

operator

parse

pattern

print

Elm pretty-printer.

span

token

type_annotation

visit

Immutable visitor trait for traversing Elm ASTs.

visit_mut

Mutable visitor trait for in-place AST transformation.