Fidelity.Toml 0.1.1

Fidelity.Toml

A fully TOML 1.0.0 compliant parser for F#, built with XParsec.

Overview

Fidelity.Toml is a pure F# implementation of a TOML 1.0.0 parser using parser combinators. It is designed to be:

• Spec-compliant: Full TOML 1.0.0 support including all data types, datetime formats, and structural features
• Pure F#: No external parsing dependencies beyond XParsec
• Self-hosting ready: Part of the Fidelity Framework toolchain infrastructure

Part of the Fidelity Framework

This library is a component of the Fidelity Framework - an ecosystem for compiling F# to native code without the .NET runtime.

Why a Separate TOML Library?

Fidelity.Toml exists as a standalone library because:

1. Self-hosting path: As the Fidelity toolchain matures toward self-hosting, every dependency must be expressible in native F#. Having a pure F# TOML parser (using XParsec) ensures the entire toolchain can eventually compile itself.

2. Shared infrastructure: Both the Firefly compiler and FsNativeAutoComplete (the LSP server) need to parse .fidproj project files. A shared library eliminates duplication.

3. General utility: A compliant TOML parser is useful beyond project files - configuration, data exchange, and more.

4. Joy: XParsec is a great library and I really dig working with it.

Installation

dotnet add package Fidelity.Toml

Or add to your .fsproj:

<PackageReference Include="Fidelity.Toml" Version="0.1.0" />

Usage

open Fidelity.Toml

// Parse a TOML string
let toml = """
[package]
name = "my-project"
version = "1.0.0"

[build]
sources = ["Main.fs", "Lib.fs"]
output = "myapp"
"""

match Toml.parse toml with
| Ok document ->
    // Access values
    let name = Toml.getString "package.name" document  // Some "my-project"
    let sources = Toml.getStringArray "build.sources" document  // Some ["Main.fs"; "Lib.fs"]
    printfn "Project: %A" name

| Error msg ->
    eprintfn "Parse error: %s" msg

Supported TOML Features

Data Types

Structural Features

API Reference

Parsing

/// Parse a TOML string into a document
val parse : string -> Result<TomlDocument, string>

Value Access

/// Get a string value by dotted key path
val getString : string -> TomlDocument -> string option

/// Get an integer value
val getInt : string -> TomlDocument -> int64 option

/// Get a float value
val getFloat : string -> TomlDocument -> float option

/// Get a boolean value
val getBool : string -> TomlDocument -> bool option

/// Get an array of strings
val getStringArray : string -> TomlDocument -> string list option

/// Get a table (sub-document)
val getTable : string -> TomlDocument -> TomlDocument option

Building from Source

git clone https://github.com/FidelityFramework/Fidelity.Toml.git
cd Fidelity.Toml
dotnet build
dotnet test

Contributing

Contributions are welcome! Please see the Fidelity Framework contributing guidelines.

License

MIT License - see LICENSE for details.

Part of the Fidelity Framework - Native F# for everyone.