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Fornax is a scriptable static site generator using type safe F# DSL to define page layouts.

Fornax is part of Ionide tooling suite - You can support its development on Open Collective.

open collective backers open collective sponsors

Open Collective

Working features

  • Creating custom data loaders using .fsx files, meaning you can use as a source of data for your site anything you can imagine, not only predefined .md or .yml files
  • Creating custom generators using .fsx files, meaning you can generate any type of output you want
  • Dynamic configuration using .fsx file
  • Watch mode that rebuilds your page whenever you change data, or any script file.


Fornax is released as a global .Net Core tool. You can install it with dotnet tool install fornax -g

CLI Application

The main functionality of Fornax comes from CLI applications that lets user scaffold, and generate webpages.

  • fornax new - scaffolds new blog in current working directory using really simple template
  • fornax build - builds webpage, puts output to _public folder
  • fornax watch - starts a small webserver that hosts your generated site, and a background process that recompiles the site whenever any changes are detected. This is the recommended way of working with Fornax.
  • fornax clean - removes output directory and any temp files
  • fornax version - prints out the currently-installed version of Fornax
  • fornax help - prints out help

Getting started

Easiest way to get started with fornax is running fornax new and then fornax watch - this will create fairly minimal blog site template, start fornax in watch mode and start webserver. Then you can go to the localhost:8080 in your browser to see the page, and edit the scaffolded files in editor to make changes. Additionally, you can take a look at samples folder in this repository - it have couple more loaders and generators that you can potentially use in your website.

Website definition

Fornax is using normal F# code (F# script files) to define any of it's core concepts: loaders, generators and config.


SiteContents is fairly simple type that provides access to any information available to the Fornax. The information is put into it by using loaders and then can be accessed in the generators.

SiteContents has several functions in it's public API:

type A = {a: string}
type B = {b: int; c: int}

let sc = SiteContents()
sc.Add({a = "test"})
sc.Add({a = "test2"})
sc.Add({a = "test3"})

sc.Add({b = 1; c = 3}) //You can add objects of different types, `Add` method is generic.

let as = sc.TryGetValues<A>() //This will return option of sequence of all added elements for given type - in this case it will be 3 elements
let b = sc.TryGetValue<B>() //This will return option of element for given type


Loader is an F# script responsible for loading external data into generation context. The data typically includes things like content of .md files, some global site configuration, etc. But since those are normal F# functions, you can do whatever you need. Want to load information from local database, or from internet? Sure, why not. Want to use World Bank TP to include some of the World Bank statistics? That's also possible - you can use in loader any dependency as in normal F# script.

Loaders are normal F# functions that takes as an input SiteContents and absolute path to the page root, and returns SiteContents:

#r "../_lib/Fornax.Core.dll"

type Page = {
    title: string
    link: string

let loader (projectRoot: string) (siteContent: SiteContents) =
    siteContent.Add({title = "Home"; link = "/"})
    siteContent.Add({title = "About"; link = "/about.html"})
    siteContent.Add({title = "Contact"; link = "/contact.html"})


Important note: You can (and probably should) define multiple loaders - they will all be executed before generation of site, and will propagate information into SiteContents


Generator is an F# script responsible for generating output of the Fornax process. This is usually .html file, but can be anything else - actually generator API just requires to return string that will be saved to file. Generators are, again, plain F# functions that as an input takes SiteContents, absolute path to the page root, relative path to the file that's currently processed (may be empty for the global generators) and returns string:

#r "../_lib/Fornax.Core.dll"
#load "../loaders/postloader.fsx"

open Html

let generate' (ctx : SiteContents) (_: string) =
    let posts = ctx.TryGetValues<Postloader.Post> () |> Option.defaultValue Seq.empty

    let psts =
        |> Seq.toList
        |> (fun p -> span [] [!!] )

    html [] [
        div [] psts

let generate (ctx : SiteContents) (projectRoot: string) (page: string) =
    generate' ctx page
    |> HtmlElement.ToString

Important note: You can (and probably should) define multiple generators - they will generate different kinds of pages and/or content, such as post, index, about, rss etc.


Configuration is a F# script file that defines when which analyzers need to be run, and how to save its output. Config.fsx file needs to be put in the root of your site project (the place from which you run fornax CLI tool)

#r "../_lib/Fornax.Core.dll"

open Config
open System.IO

let postPredicate (projectRoot: string, page: string) =
    let fileName = Path.Combine(projectRoot,page)
    let ext = Path.GetExtension page
    if ext = ".md" then
        let ctn = File.ReadAllText fileName
        ctn.Contains("layout: post")

let staticPredicate (projectRoot: string, page: string) =
    let ext = Path.GetExtension page
    if page.Contains "_public" ||
       page.Contains "_bin" ||
       page.Contains "_lib" ||
       page.Contains "_data" ||
       page.Contains "_settings" ||
       page.Contains "_config.yml" ||
       page.Contains ".sass-cache" ||
       page.Contains ".git" ||
       page.Contains ".ionide" ||
       ext = ".fsx"

let config = {
    Generators = [
        {Script = "less.fsx"; Trigger = OnFileExt ".less"; OutputFile = ChangeExtension "css" }
        {Script = "sass.fsx"; Trigger = OnFileExt ".scss"; OutputFile = ChangeExtension "css" }
        {Script = "post.fsx"; Trigger = OnFilePredicate postPredicate; OutputFile = ChangeExtension "html" }
        {Script = "staticfile.fsx"; Trigger = OnFilePredicate staticPredicate; OutputFile = SameFileName }
        {Script = "index.fsx"; Trigger = Once; OutputFile = NewFileName "index.html" }


How to contribute

Imposter syndrome disclaimer: I want your help. No really, I do.

There might be a little voice inside that tells you you're not ready; that you need to do one more tutorial, or learn another framework, or write a few more blog posts before you can help me with this project.

I assure you, that's not the case.

This project has some clear Contribution Guidelines and expectations that you can read here.

The contribution guidelines outline the process that you'll need to follow to get a patch merged. By making expectations and process explicit, I hope it will make it easier for you to contribute.

And you don't just have to write code. You can help out by writing documentation, tests, or even by giving feedback about this work. (And yes, that includes giving feedback about the contribution guidelines.)

Thank you for contributing!

Build process

  • You need .NET Core 3.0 SDK
  • Run dotnet tool restore to restore the .NET Core 3 local tools defined at .config/dotnet-tools.json
  • To build the project run dotnet fake build
  • To run unit tests run dotnet fake build -t Test

Contributing and copyright

The project is hosted on GitHub where you can report issues, fork the project and submit pull requests. Please read Contribution Guide

The library is available under MIT license, which allows modification and redistribution for both commercial and non-commercial purposes.

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.

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