Riff: Early Ideas and Motivation

Darryl Abbate

This post is transposed from part of a presentation I gave as part of an Undergraduate Seminar. Feel free to check out Riff’s website to learn more about the project.

What is Riff?

Riff is a general-purpose programming language I started developing around April 2020 as a hobby project. Riff is dynamically-typed and designed with a focus on prototyping and command-line usage.

Design Goals


int main(void) {
    int x = 0;
    x * 2 + 1;  // What happens to this?
    return 0;

This looks like a typical expression, but it’s invalid. It’s not being assigned to a variable, it’s not part of a conditional expression, nothing. A C compiler will probably compile it (Clang raises a warning) and Java throws an error.


x = y + z
x * i       // Print

My idea was to give some kind of functionality to these otherwise invalid expression statements. Given the focus on being a command-line protoyping tool, it made sense to simply print the results of these “atypical” expression statements. This gives the language a kind of “interactive” REPL-like feel without having to enter an interactive session.

Why Not Use <existing_language>?

Even if you just wanted to write one-liners, many tools and languages already support a similar functionality.

$ perl –e 'print(30/0.5+10, "\n")'
$ awk 'BEGIN{print 30/0.5+10}'
$ python –c 'print(30/0.5+10)'
$ ruby –e 'puts 30/0.5+10'
$ lua –e 'print(30/0.5+10)'
$ riff '30/0.5+10'

These all work perfectly fine. All of these commands will produce the same result. However, the Riff example is noticeably simpler; I feel any given programmer would be more likely to remember its syntax over the other languages’ provided examples (assuming they don’t actively program in those languages).


I don’t want to just make a command-line calculator. I want it to be actually useful. This means the language needs standard facilities like control flow, compound data structures, user-defined functions, a standard library of functions, etc. Does this “implicit printing” functionality impede the ability to implement these basic language features?1

At this point in the presentation, I briefly spoke about the language’s features before wrapping up with a simple benchmark, placing Riff in the ballpark of Lua in terms of performance.

  1. While this wasn’t really a serious question for anyone familiar with languages and compilers, it’s an understandably natural question for a group of undergraduate students. For what it’s worth, since I started developing Riff, I’ve discovered two other languages with a similar “implicit printing” functionality: bc and HolyC.[return]