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Discussion on: Language Features: Best and Worst

610yesnolovely profile image
Harvey Thompson

Add to that:

  • Proper static type system with generics, abstract type members, variadic types, tuple types, function types, a sound and complete type system with set-like operations (and, or, not).
  • Flow typing: a variables deduced type is refined through flow control.
  • Garbage collection (of some kind)
  • I agree on no exceptions, use types.
  • Compiler-as-a-library
  • Macros and other meta-programming
  • Incremental compilation
  • Interactive prompt
  • JIT compilation, AOT compilation and scripting
  • Support Language Server Protocol (and check it works in vim, emacs, vscode)
  • Support Debugger Access Protocol (which requires a whole debugger, and debug symbol system)
  • Support memory, cpu, cache profiling tools out of the box (eg. valgrind et. al)
  • Support and/or built-in testing
  • Support and/or built-in quality metrics
  • Make it open and freely available

I've been designing and building languages (now full time) for many years. You'll find you can end up adding an infinite list of things.

My advice, try writing a very simple Lisp interpreter: it can be done in under a day. Then try adding a few things.

You might also want to check out LLVM, which has a tutorial Implementing A Language With LLVM

My other advice, as soon as possible "Eat Your Own Dogfood". The programming language, compiler services, and all it's libraries should be written itself. To do this write a bare minimum language compiler from your language to C, C++, Java or whatever (C++ did this initially with "cfront"). Then rewrite that simple pre-processor in your new language. Then add more features.

This is the best and most efficient way to validate your work - if you like using your own language more than some other, you are on possibly on the right track.

awwsmm profile image
Andrew (he/him) Author

Thanks for all the advice. I'm going to have a huge list of things to research before I even think about starting this project. I'm sure I'll come back to your comment more than a few times.

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610yesnolovely profile image
Harvey Thompson

I forgot to say the most influential book for me are:

  • "Programming Languages: An Interpreter Based Approach" by Samuel N Kamin - though it says it's about Interpreters, it's really looking at how to implement language features for various languages. This makes you feel like you could do it yourself, because it explains each feature and gives example code. One of the first books I read on the subject.

  • "Types and Programming Languages" by Benjamin C Pierce. Totally opposite and quite heavy reading. Assumes you can do degree level set-theoretic logic - but this book basically tells you how to build a proper type system from a mathematical perspective. The concepts are key, so it's possible to read and gloss over the maths. Often academia has the future or bleeding edge hidden in research papers, so it's worth reading these also, even if the maths goes way over ones head.

As I mentioned, Lisp is a great place to start because it has a very simple lexical and syntactical grammar, and the semantics can be expressed in very minimally. I quick google search gave me: Lisp in Less Than 200 Lines Of Code

Don't research absolutely everything to begin with, it's too overwhelming a subject. The basics are covered in the "Dragon Book":

  • Lexical analysis (see flex, antlr, re2c)
  • Syntax/Parsing (bison, antlr)
  • Semantic analysis (you're on your own here, it's too language specific)
  • Type systems (if you're going static typing, which I would highly recommend)
  • Code Generation (see LLVM, it does everything you'd need)

Another thing I tend to do is read/use a lot of languages and steal... err... leverage... ideas. Most also have their compilers and libraries open sourced. Some interesting languages: Swift, C#, Kotlin, Rust, Julia, Scala, Clojure, Erlang.

Don't be daunted, the subject, like most, is quite deep and involved when you really look into it.

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awwsmm profile image
Andrew (he/him) Author

Wow! Thanks a lot, Harvey! This is a great list of books. I really appreciate it. I'll definitely have a look at Lisp.