which languages have a REPL and Type Annotation? (lemmy.blahaj.zone)

submitted 2 months ago by jh29a@lemmy.blahaj.zone to c/programming_languages@programming.dev

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(as an interested university student:) From Programming at a small scale in Javascript and Logo¹, I have gathered that not knowing what type something is can be annoying. They also have REPLs, which is pretty nice. From various blog posts and debugging Rust programs, I have learned that not having a REPL can be annoying. Are there languages that have both?

(¹ Logo is a "lisp" with omitable parentheses, where these also don't define runtime-mutable s-expressions, lists are in brackets, and also Logo doesn't have structs, giving it bad maintainability outside of not having Type Annotation too)

Candidates

C# : Does it have a repl?
Java in BlueJ somehow
sometimes people just put Lisp or Lua in their C/Rust++ program (emacs, shenzhen I/O(game)), this accomplishes a similar task of making some debugging or scripting code faster to compile/interpret, but slower to run

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[-] mobotsar@sh.itjust.works 5 points 2 months ago

If only it had the one thing of OCaml does that's actually important: ML modules.

Okay, I'm being kinda glib. Ocaml has plenty of other stuff going for it, and F# is a great, productive language, but its biggest weakness is something it doesn't have.

[-] expr@programming.dev 3 points 2 months ago

That, or Haskell's typeclasses (which serve much of the same need). Without one or the other you lose out on a lot of expressive power.

[-] mobotsar@sh.itjust.works 2 points 2 months ago* (last edited 2 months ago)

Modules are substantially more expressive than typeclasses, but yes, type classes get you a decent part of the way there.

[-] expr@programming.dev 2 points 2 months ago

They have different sets of tradeoffs and prioritize different things. Nevertheless, you can express typeclasses with the module system just as you can express the module system with typeclasses (using modern Haskell language extensions to the typeclass system). One is not more expressive than the other. You give me any usage of the module system, and I can show you how it can be done with typeclasses.

[-] mobotsar@sh.itjust.works 1 points 2 months ago

Hah, I was afraid you would say that when I wrote my comment. I don't mean expressive in the sense of "can encode X"; I mean expressive in the sense of "can nicely encode X". The bullshit you have to put yourself through in Haskell to get the core niceties of modules is unpalatable (to me, anyway).

[-] expr@programming.dev 2 points 2 months ago

You likely aren't familiar with modern Haskell, tbh. Things have changed a lot in the last handful of years. If you give me an example, I can show you how it can be done pretty reasonably (I write Haskell professionally, fwiw).

[-] Pencilnoob@lemmy.world 2 points 2 months ago

What's the big thing that enables, I've played with so many languages but I've never actually used OCaml enough to understand that feature

[-] mobotsar@sh.itjust.works 1 points 2 months ago

Modules are called such because they enable modularity. https://www.pathsensitive.com/2023/03/modules-matter-most-for-masses.html?m=1 that link will explain it more thoroughly than I want to or probably could.

[-] Pencilnoob@lemmy.world 1 points 2 months ago

Ah ok, we're getting into Coq proofs. I'm trying to work through Software Foundations but it's so tricky! I feel like I need an intellect potion to get it

this post was submitted on 26 Oct 2025

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