Opal

Opal is an open source programming language created in 1994.

Source code:

git clone https://github.com/TU-Berlin/opal

#972on PLDB

30Years Old

14Repos

OPAL (OPtimized Applicative Language) is a functional programming language first developed at the Technical University of Berlin.. Read more on Wikipedia...

Opal Wikipedia page
Opal is developed on GitHub and has 6 stars
There are at least 14 Opal repos on GitHub
Opal first developed in https://github.com/TU-Berlin
file extensions for Opal include opal
The Google BigQuery Public Dataset GitHub snapshot shows 9 users using Opal in 10 repos on GitHub
GitHub supports syntax highlighting for Opal
Read more about Opal on the web: 1.

Example from Linguist:

-- Deepak Chopra nonsense text generator
-- see https://github.com/StoneCypher/DeepakChopra_Opal/

starts = ["Experiential truth ", "The physical world ", "Non-judgment ", "Quantum physics "]
middles = ["nurtures an ", "projects onto ", "imparts reality to ", "constructs with "]
qualifiers = ["abundance of ", "the barrier of ", "self-righteous ", "potential "]
finishes = ["marvel.", "choices.", "creativity.", "actions."]

alert starts.sample + middles.sample + qualifiers.sample + finishes.sample

Example from Wikipedia:

IMPLEMENTATION GCD
   IMPORT Nat COMPLETELY
   DEF GCD(a,b) == IF a % b = 0 THEN b
                       ELSE IF a-b < b THEN GCD(b,a-b)
                           ELSE GCD(a-b,b)
                       FI
                   FI

Feature	Supported	Token	Example
Comments	✓		-- A comment
Line Comments	✓	--	-- A comment
Semantic Indentation	X

Opal - Programming language

Language features