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Fun2
Fun2 is an esoteric dialect of JavaScript, created by User:AndrewBayly, and successor to Fun. Like Fun, a Fun2 program consists entirely of function calls. Fun2 extends Fun by adding a two-layer architecture: an S-expression layer for constructing Lisp data structures, and a Lisp interpreter layer that evaluates them. The result is a language that is genuinely Lisp, expressed in Fun's function-call syntax.
Turing completeness
Fun2 is Turing-complete. This follows directly from the fact that the interpreter layer implements a variant of tinylisp, which is itself Turing-complete. Unlike Fun, no explicit brainfuck translation is needed to establish this.
Implementation
The Fun2 interpreter is implemented as two JavaScript files: the S-expression layer and the interpreter layer. Both are plain JavaScript libraries with no dependencies. A Fun2 program is a JavaScript file that includes both libraries and calls RUN(...).
An interactive implementation is available at andrewbayly.github.io/esolangs/Fun2/.