Source Code of FEEL parser/interpreter in tasklist-app?

Camunda Platform 8 Topics
1

Hi,

I created a form with the forms editor with an condition field, e.g. “Hide if” is set to =myCheckbox. This hides the field in the task list app using 8.2.0-alpha3 whenever the checkbox with the variable “myCheckbox” is checked. Perfect.

Where can I find the source of the FEEL Parser/Interpreter that evaluates the FEEL expression? I know that task-list is closed source currently but I was hoping to find the FEEL Parser/Interpreter with an open source license.

Best,
Tobias

2

Hey @tobiasschaefer

I guess you’re looking for the GitHub - camunda/feel-scala: FEEL parser and interpreter written in Scala engine created by @Philipp_Ossler

There is also a feel playground. Try out and learn DMN FEEL - FEEL Playground which might be interesting when playing with feel expressions :slight_smile: Created by @nikku

Hope that helps.

Greets
Chris

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3

Thanks @Zelldon for that fast response!

Scala is a JVM based language and it makes sense that this is being used by the Zeebe process engine.

However, the task-list app is browser-based and there is no network traffic to any backend when evaluating the FEEL expressions in the task-list app UI. So are you using scala.js to compile feet-scala to JavaScript or is there possibly another implementation being used? Maybe this could be related to the “feelin” by @nikku (thanks for that hint!)

Best,
Tobias

4

Yes. Tasklist uses a JS-based FEEL implementation.

I guess it uses this: GitHub - bpmn-io/feelers: A text templating solution built on top of FEEL
Or: GitHub - nikku/feelin: A DMN FEEL parser and interpreter written in JavaScript

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5

Thanks @Philipp_Ossler, indeed, form-js is using feelin here. bpmn-io/feelers is currently under development and not used in form-js already. This will follow in one of the future releases.

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