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Version: 1.16 (unreleased)

Get Started

Welcome to the documentation of the FEEL-Scala engine!

If you're new and don't know anything about FEEL then have a look at What is FEEL first.

If you want to know how to write FEEL expressions then have a look at the Language Guide.

If you want to integrate the FEEL engine in your application then have a look at the Developer Guide.

FEEL REPL

The easiest way to try out your FEEL expressions in development is to use the REPL (Read-Eval-Print-Loop) of the FEEL engine. It is a simple script based on Ammonite (aka Scala Scripting) that downloads the dependency to the FEEL engine and initialize it for you.

the-feel-repl

Install

  • Download Ammonite: http://ammonite.io/#Ammonite-REPL
    • On Linux:
    sudo sh -c '(echo "#!/usr/bin/env sh" && curl -L https://github.com/com-lihaoyi/Ammonite/releases/download/2.4.0/2.13-2.4.0) > /usr/local/bin/amm && chmod +x /usr/local/bin/amm' && amm
    • On Mac:
    brew install ammonite-repl
  • Download the script feel-repl.sc or clone the Git repository

Usage

Run the following script to start the REPL:

amm --predef feel-repl.sc

In the REPL, use one of the following functions to evaluate a FEEL expression:

feel("1 + 3")
// evaluate an expression without any context

val context = Map("x" -> 3)
feel("1 + x", context)
// evaluate an expression with a map-based context

feel("1 + x", "{ \"x\": 3}")
// evaluate an expression with a JSON context

feel(""" date("2020-04-06") + duration("P3D") """)
// evaluate an expression ignoring any quotes in the expression

//----------------------------------------------------------------------

unaryTests("> 3", 5)
// evaluate a unary-tests with a given input value

unaryTests("> 3", 5)
// evaluate a unary-tests with a given input value

val context = Map("x" -> 3)
unaryTests("> x", 5, context)
// evaluate a unary-tests with a given input value and map-based context

unaryTests("> x", "5", "{ \"x\": 3}")
// evaluate a unary-tests with a given JSON input value and JSON context