In my previous Dada blog post, I talked about how Dada enables composable sharing. Today I’m going to start diving into Dada’s permission system; permissions are Dada’s equivalent to Rust’s borrow checker.

Goal: richer, place-based permissions

Dada aims to exceed Rust’s capabilities by using place-based permissions. Dada lets you write functions and types that capture both a value and things borrowed from that value.

As a fun example, imagine you are writing some Rust code to process a comma-separated list, just looking for entries of length 5 or more:

OK, let’s talk about sharing. This is the first of Dada blog posts where things start to diverge from Rust in a deep way and I think the first where we start to see some real advantages to the Dada way of doing things (and some of the tradeoffs I made to achieve those advantages).

Let’s continue with working through Dada. In my previous post, I introduced some string manipulation. Let’s start talking about permissions. This is where Dada will start to resemble Rust a bit more.

Following on my Fun with Dada post, this post is going to start teaching Dada. I’m going to keep each post short – basically just what I can write while having my morning coffee.¹

Waaaaaay back in 2021, I started experimenting with a new programming language I call “Dada”. I’ve been tinkering with it ever since and I just realized that (oh my gosh!) I’ve never written even a single blog post about it! I figured I should fix that. This post will introduce some of the basic concepts of Dada as it is now.

Before you get any ideas, Dada isn’t fit for use. In fact the compiler doesn’t even really work because I keep changing the language before I get it all the way working. Honestly, Dada is more of a “stress relief” valve for me than anything else¹ – it’s fun to tinker with a programming language where I don’t have to worry about backwards compatibility, or RFCs, or anything else.

That said, Dada has been a very fertile source of ideas that I think could be applicable to Rust. And not just for language design: playing with the compiler is also what led to the new salsa design², which is now used by both rust-analyzer and Astral’s ty. So I really want to get those ideas out there!