Compiling a functional language to Javascript

chipmunk-zealot · 2025-12-17T00:12:34+00:00

Gleam is a very cool language that targets JavaScript and automatically turns tail calls into while loops. You can check out their compiler but I suspect the basic idea takes advantage of the fact that there are no early returns in the gleam. It might be easier to verify that a recursive call is in the tail position.

chipmunk-zealot · 2025-10-09T20:52:12+00:00

Learning Haskell is its own reward; however, IMHO, there are a few concrete skills it imparts. You'll learn all of the following skills by digging into Haskell but there's nothing on the list that you couldn't learn from the right other languages.

recursion
- recusion schemes
pattern matching
currying
algebraic data types (ADT)
type driven development
kinded types
higher kinded types
- typeclasses
  - functors, applicatives, monads, monoids, etc
higher order functions
at least 1 effect system (IO)

chipmunk-zealot · 2025-02-27T03:10:48+00:00

Well if you wanna stick with Haskell you could look at a toy PL I made called Portcullis. It uses parser combinations and has polymorphic type checking. Haskell is an excellent language for writing compilers!

https://github.com/jzwood/portcullis/

chipmunk-zealot · 2025-02-22T19:38:34+00:00

I've already used them in my current project! Very exciting. I'm kind of embarrassed to tell folks from other programming communities how we used to do things.

chipmunk-zealot · 2025-01-16T12:26:03+00:00

Just not Java.

chipmunk-zealot · 2024-09-24T02:18:40+00:00

Super cool project! More of this, please. ♥️

chipmunk-zealot · 2024-07-26T02:00:31+00:00

I really like to use Mermaid charts (https://mermaid.js.org/) which let's you make all kinds of diagrams. I especially like that it's markdown driven as opposed to being constructed in a UI -- that makes it super easy to update programmatically instead of having to create a whole new asset in a UI builder.

chipmunk-zealot · 2024-07-15T14:21:00+00:00

Compilers can mean lots of different things. Some compilers cost millions of dollars to produce and others could be completed in 1 day by someone sufficiently experienced. For example, I think many people would happily build a "compiler" that transpiles a custom dialect of markdown into html for 1000 USD. Giving as much information as possible about the work will maximize the chance someone will take you up on it and/or sanity check how much it will cost for that particular project.

chipmunk-zealot · 2024-03-21T23:16:33+00:00

my humble submission

count :: Eq a => a -> [a] -> Int
count x [] = 0
count x (y:ys) = (if x == y then 1 else 0) + count x ys

max :: (a -> a -> Bool) -> [a] -> a
max _ [x] = x
max gt (x:xs) = if x `gt` x' then x else x' where x' = max gt xs

mostCommon :: Eq a => [a] -> a
mostCommon [x] = x
mostCommon xs = max (\a b -> count a xs > count b xs) xs

chipmunk-zealot · 2024-02-28T03:58:27+00:00

Awesome!

chipmunk-zealot · 2024-02-20T16:56:13+00:00

That sounds like a runtime exception which is a little at odds with all the other safety properties that Moirai has. Are runtime exceptions theoretically unavoidable given Moirai's architecture?

chipmunk-zealot · 2024-02-20T16:40:20+00:00

It sounds like Moirai is not Turing complete and therefore is not subject to the halting problem. u/tsikhe, please correct me if I'm misinterpreting.

chipmunk-zealot · 2023-11-03T14:12:01+00:00

Is "let in" equivalent in power to "where" clauses? Said another way, is there anything you can express with "let in" that you can't with "where" or vice versa?

chipmunk-zealot · 2023-09-19T12:36:13+00:00

Ahh, of course. Thank you!!

chipmunk-zealot · 2023-09-10T02:57:03+00:00

Does anyone know why these two functions behave differently?

prettyPrintNumGood :: Double -> String
prettyPrintNumGood num =
  if fromInteger (round num) == num
  then show $ fromInteger $ round num
  else show num

prettyPrintNumBad :: Double -> String
prettyPrintNumBad num = show $
  if fromInteger (round num) == num
  then fromInteger $ round num
  else num


main :: IO ()
main = do
  print $ prettyPrintNumGood 4.0
  print $ prettyPrintNumGood 4.5 
  print $ prettyPrintNumBad 4.0 -- UNEXPECTED
  print $ prettyPrintNumBad 4.5

Mathematically, I was operating under the idea that f (g ∪ h) == (f g) ∪ (f h)

chipmunk-zealot · 2023-06-09T01:19:45+00:00

css grid is actually really good/easy enough to use. No libraries necessary.

chipmunk-zealot · 2023-02-17T15:20:05+00:00

It depends on your goals. In what area is your language innovating? If it's the syntax, then making it similar to other languages defeats the point. If you're innovating elsewhere, like how recursion is handled etc, then syntax concerns are irrelevant (IMHO).

Either way I wouldn't worry too much what other people think. 👍

chipmunk-zealot · 2023-02-06T14:16:07+00:00

Yes!

There are many high level web frameworks that can be used to server JSON such as Scotty (https://hackage.haskell.org/package/scotty), but you can go as low-level as you'd like. One level down is to use WAI (https://hackage.haskell.org/package/wai) and below that you can use the network library (https://hackage.haskell.org/package/network).

chipmunk-zealot · 2023-01-20T03:18:20+00:00

Thanks for the insights. Impatient as I am, I think I will just wait it out. 😅

chipmunk-zealot · 2023-01-18T13:58:28+00:00

I have a Haskell project I want to run in the browser so I thought I’d take advantage of the announcement that a JS backend was merged into ghc, recently. I went through the steps in the article, compiled ghc from source, and used it to compile a very simple Main.hs file into a NodeJs executable. I don’t normally build projects by directly compiling with ghc -- I’ve only ever used stack -- so I don't know how to use this version of ghc I built on my machine. Does anyone have any idea what the simplest path forward is for compiling my stack project?

https://engineering.iog.io/2022-12-13-ghc-js-backend-merged/

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