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Comment by weatherlight | Hacker News Reader

because SML is awesome, isn't going to change and is simple. you can learn the syntax in an afternoon, and really focus on learning FP semantics.

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Albeit little, installing SML still requires some anount of gymnastics, google searching, and copying stuff from SO, GH Gists, etc.

Yes, I agree broadly with the line of thinking that says- if you are learning FP, you must be willing to do these, but a beginner might be disheartened and turned away- especially as someone learning alone.

totally fair!

The problem that is extremely verbose though. OCaml is much more concise.

Both languages encourage a concise, functional programming style but with different flavors and toolsets. They are comparable, in terms of verbosity.

I think these are correct implementations of the tower of Hanoi.

OCaml

    let rec hanoi n source target auxiliary =
      if n > 0 then begin
        hanoi (n - 1) source auxiliary target;
        Printf.printf "Move disk from %s to %s\n" source target;
        hanoi (n - 1) auxiliary target source
      end

SML

    fun hanoi n source target auxiliary =
      if n > 0 then (
        hanoi (n - 1) source auxiliary target;
        print ("Move disk from " ^ source ^ " to " ^ target ^ "\n");
        hanoi (n - 1) auxiliary target source
      )

function definition, if expressions, recursion are more concise in SML, string interpolation is nicer in OCaml

You SML code is incorrect, shows that you actually never coded anything in SML. SML requires that "if" always contains "else" clause (which is the norm for many functional languages). And this kind of stuff which makes SML unnecessarily verbose (OCaml has for operators, single line let definitions that do not require you to make use val and fun for different type definitions etc.).

I did Programming Languages, Part A, (to learn FP semantics) many years ago. It doesn't show I never coded anything in SML, it shows I made a mistake :/ .I no longer have Standard ML on my machine.

I thought having the `let` keyword encompass `fun` and `val.` was needlessly confusing. It's not concise. if `let` can mean so many things why not just do what Haskell did.

Again.. it not "so much more verbose." which was the initial point.

but I concede, my SML code is in fact incorrect.

No SML is more verbose, is pretty obvious. A simple "for" in ocaml could save lots boilerplate doing trivial recurison.

Functional programmers tend to use recursion instead of explicit loops with implicit state, and it's wise to regard for loops with suspicion since it can't return anything.

Standard ML as the language of instruction is a vehicle for teaching FP semantics, not imperative ones.

Also, Tower of Hanoi is a classic problem that's well suited for recursion.

You do not need to school me about why "for" is not pure functional - as soon as you understand that it is syntactic sugar, you are fine; IO is also impure, so if you insisting in purity then the only option is Haskell.

If you want to be pedantic, in functional programming there is no such a thing as "return value", as there is no such a thing as statement, only expressions. And expressions always _have_ values, they do not _return_ them.

I agree that SML is better for teaching than OCaml no doubt about it.

I mean, it is pointless to continue this conversation; you did not use SML for a long time - I did use it last time last year, and I can attest, it is extremely impractical compared to any other FP language today.

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