Language

January 12, 2024

This post explores how to work and interact with the language.

My goal for 2024 is to implement a simple programming language that compiles to WebAssembly and that I can use to solve at least one Advent of Code problem. In this post I try to nail down, how to language should look and how it can be used.

I have to confess something. I am undecided. I have been programming in many languages and syntactically I still like Clojure (Lisp in general) and Haskell the most. Here are two very simple examples.

-- Haskell
hello name = 
    "Hello " <> name <> "!"
    
hello "Matthias"

; Clojure (replace (name) with [name])
(defn hello (name)
    (str "Hello " name "!"))
    
(hello "Matthias")

Which one to build?

So which one should I use to base my language on?

The reason I like Haskell syntactically is, that it reduces most programming constructs to their bare essence. When everything is immutable and therefore a value, there is no need for a keyword to denote that something is immutable¹. When a “variable assignment” (x = 5) can be viewed as a function, that always returns the same value (5 in the example), there is no need to differentiate between functions and variables. When every programming construct returns a single value, there is no need for braces. I could go on, but trying to reduce things to their essence is inspiring and makes the language simpler, which is always good.

The reason I like Lisps syntactically is, that besides a few primitives (numbers, booleans, strings, characters), everything is a list. That means the language is very consistent. Semantically, the first element of every list is a function and all other elements are their arguments. That’s all there is to it. That also means to add 3 numbers it’s possible to just write (+ 3 5 6) instead of 3 + 5 + 6. The latter may feel more familiar, but because we and a compiler have to keep track of precedence rules, it is more complex (* should be called before +).

Conclusion

I should have written much more about data types, expression based languages and much more. Unfortunately, I don’t have much time this week, so this post is going to be a bit short.

To decide which syntax to use, there is one argument that trumps all others for me at the moment. Since I am a beginner in implementing compiler like programs, parsing a Haskell-like syntax is more involved than parsing a Lisp. In a Lisp, there is no need to think about indentation levels and operator precedence.

That’s why I will be going with a Lisp like syntax.