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A fresh retake of the base React DSL used within Elmish applications, optimized for happiness
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  1. F# 98.4%
  2. Other 1.6%
Branch: master
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Feliz (beta) Nuget

A fresh retake of the base React DSL used within Elmish applications, optimized for happiness.

Here is how it looks like:

let render state dispatch =
    Html.div [ "main" [ style.padding 20 ]
        prop.children [

            Html.button [
       [ style.marginRight 5 ]
                prop.onClick (fun _ -> dispatch Increment)
                prop.text "Increment"

            Html.button [
       [ style.marginLeft 5 ]
                prop.onClick (fun _ -> dispatch Decrement)
                prop.text "Decrement"

            Html.h1 state.Count


  • Consistent formatting: no more awkward indentation using two lists for every element.
  • Discoverable attributes with no more functions, Html attributes or css properties globally available so they are easy to find.
  • Proper documentation: each attribute and CSS property
  • Fully Type-safe: no more Margin of obj but instead utilizing a plethora of overloaded functions to account for the overloaded nature of CSS attributes, covering 90%+ of the CSS styles, values and properties.
  • Included color list of most commonly used Html colors in the colors module.
  • Compatible with the current DSL used in applications.
  • Compatible with Femto.
  • Approximately Zero bundle size increase where everything function body is erased from the generated javascript unless you actually use said function.

Overloaded elements

When you want to display a single string or number simply use:

Html.h1 state.Count

Html.div "Hello there!"

You could also expand the attribute:

Html.h1 [
    prop.className "title"
    prop.children [
        Html.text "Hello there"

Which is the same as:

Html.h1 [
    prop.className "title"
    prop.text "Hello there"

Single element child works too as input:

Html.h1 (Html.strong "I am bold")

// same as

Html.h1 [
    prop.children [ Html.strong "I am bold" ]

Input elements are also easy to work with:

Html.input [
    prop.className "input"
    prop.valueOrDefault state.Crendentials.Password
    prop.onChange (SetPassword >> dispatch)

Html.input [
    prop.className "input checkbox"
    prop.valueOrDefault state.RememberMe // boolean
    prop.onChange (SetRememberMe >> dispatch) // (bool -> unit)

Here the onChange property is overloaded with the following types

// generic onChange event
type onChange = Event -> unit
// onChange for textual input boxes
type onChange = string -> unit
// onChange for boolean input boxes, i.e. checkbox
type onChange = bool -> unit

Type-safe style attributes

let customStyles = [
        style.fontSize 20
        style.borderRadius 15
        style.borderRadius (length.px 10)
        style.margin 10
        style.margin (length.px 10)
        style.margin(10, 10, 10, 20)
        style.margin(10, 10, 10)
        style.margin(10, 10)
        style.width 10
        style.height 100
        style.height (length.vh 50)
        style.height (length.percent 100)
        style.boxShadow(0, 0, 10, colors.gray)
        style.boxShadow(10, 10, 0, 5,
        style.backgroundColor "#FFFFFF"
        style.border(3, borderStyle.dashed, colors.crimson)
        style.color "#000000"

Missing an element, an attributes or a style?

Please file an issue, because it should be there!

Different ways of specifying the classes of elements

prop.className "button" // => "button"
prop.className [ "btn"; "btn-primary" ] // => "btn btn-primary"
prop.className [ true, "conditional"; false, "falsy"; true, "class" ] // => "conditional class"

The property className has overloads to combine a list of classes into a single class, convenient when your classes are bound to values so that you do not need to concatenate them yourself.

Conditional and styles

The library includes two convenient functions to apply classes or styles conditionally on elements:

Html.div [
    prop.styleList [
        true, [ style.margin 10 ]
        state.Count >= 10, [
            style.fontSize 20
        state.Count >= 20, [
            style.fontSize 30
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