elm-handlebars

Elm-Handlebars is a dialect of the Handlebars templating language for Elm

It uses a template and a json input to generate a String.

<p>{{firstname}} {{lastname}}</p>

A handlebars expression is a {{, some contents followed by a }}. These expression will be then replaces with values from the json.

Installation & First Steps

To install, type in elm install Orasund/elm-handlebars. If you will need to work with json: elm install elm/json.

You can now start using the language by providing a json file and a template.alias

case 
    "{"firstname":"Yehuda","lastname":"Katz"}"
    |> Json.Decode.decodeString Json.Decode.value
of
    Ok value ->
        case
            value
            |> Handlebars.compile Handlebars.defaultConfig
                "<p>{{firstname}} {{lastname}}</p>"
        of
        Just string ->
            string
        Err err ->
            err
                |> Handlebars.errorToString
            
    Err err ->
        Json.Decode.errorToString err

Elm-Handlebars vs. Handlebars.js

Elm-Handlebars is a subset of the original handlebars language.

Missing features are:

• 0-argument helpers This way the name conflicts between helpers and fields are avoided

• each block helper It is functionally the same as a normal block but adding the feature would have broken the consistancy of helpers in general.

• with block helper There are a lot of oddities with this feature.

  1. It has its own syntax (introducing the as keyword) that does not really seam that useful.
  2. It can be abused to essentially a let expression (binding any constant value to a variable)
  3. The indended use, namely simplifing nested expressions, can be implemented with a simple helper without needing any special behaviour.

  Instead Elm-Handlebars ships with a different helper called the inside helper that can be used the change the context of a block.

• logs expression helper This helper would have been hard to implement. Though, it can be added quite easily as a custom helper. Therefore, its not included as a default helper.

• Html escaping Again, this can be done easily as a custom helper. Having it as a core feature assumes that the output target is Html.

• Inline blocks The original syntax is odd, to say the least. So instead Elm-Handlebars comes with an inline block helper.

• Comments No real reason. Please open an issue or create a PR if you need this feature.

• Partical Not included for time sake. Please open an issue or create a PR if you need this feature.

• The else expression This expression is used very inconsistanly. The original intent surely was to make the syntax a bit nicer. But there are so many special cases, that adding this feature felt not really helpful.

  Instead Elm-Handlebars comes with a not expression helper that can produces the same results (maybe syntactically not as nice, but semantically very clear).

• @this keyword Can practically be replaced with @index

• raw block Can be replaced by a pre-processing language (like plain old Elm).

• Literal segments Please use pre-processing to rename any fields that use special characters. You can how ever use nummers to reference a specific element in a List.

• Literal expressions Again this should be done by pre-processing. Plans are to maybe have a way to provide template with a companion pre-processor. Open an issue or create a PR if you are interested in this feature.

Contribute & Fund

If you need a new feature or found a bug, please open a new issue. I will look at it whenever i've got time.

If the issue is really important to you, then you have two options.

• You can either create a PR yourself.
• Or donate some money via issueHunt to increase the insentive for myself or someone else to tackle the problem for you.