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Standard ML in 2020

notes.eatonphil.com

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Re: Standard ML in 2020

#71

Post by Munksgaard »

yakubin wrote: post #15

I've recently picked it up, reading "ML for the working programmer". The language is fairly simple, everything just fits. However: 1. Both Vim and Emacs are horribly annoying with their automatic indentation for SML. There is a lot of fighting against the editor in this department. In Emacs e.g. you have to delete whitespace all the time, because otherwise you'd have top-level function definitions shifted 80 characte…

> 1. Both Vim and Emacs are horribly annoying with their automatic indentation for SML. There is a lot of fighting against the editor in this department. In Emacs e.g. you have to delete whitespace all the time, because otherwise you'd have top-level function definitions shifted 80 characters to the right.

I've used sml-mode in Emacs for years, and I've never had the problem you're describing. On the contrary, I find sml-mode to be quite adequate for my needs. Can you elaborate a bit on what's causing you problems?

Edit: Ah, I see what you're saying. After finishing a function definition and starting a new, the cursor is wildly indented, that's true. But if you just type `fun` and press tab, sml-mode automatically indents the definition correctly.

> 2. I've used Poly/ML and SML/NJ so far. Both of them are purely interactive, meaning I can't just compile a program into ELF and ship it somewhere else without the compiler. That makes it a no-go for me for real-world use.

I can recommend MoSML for interactive development. It can also produce compiled binaries. When I want to produce efficient compiled code, I usually use MLton.

> 3. The interactive modes of Poly/ML and SML/NJ don't support readline shortcuts. They are the most cumbersome REPLs I've ever used.

Use the REPL in emacs, it's excellent.

> 4. Inline type declarations (as opposed to Haskell-style type declarations on a separate line) are very noisy - they make reading the code harder. Omitting them (which is the rule in SML in practice) leads to hard-to-decipher compilation errors when you write a new piece of code and you made an error somewhere which confused the type-inference about your intentions. Suddenly forgetting about a word or a set of parentheses in one function results in errors in another perfectly-good function. It's the horror of C++ templates all over again.

I agree, this is a pain point. I usually leave type declarations in comments before the definitions, but that of course has obvious drawbacks.

Re: Standard ML in 2020

#73

Post by riffraff »

barrister wrote: post #19

Here is a paper[1] written by Andreas Rossberg, specification author of Web Assembly, that discusses the defects in the definition of Standard ML. I believe he tried to address many of these issues with Alice ML[2]. [1] https://people.mpi-sws.org/~rossberg/papers/sml-defects-2013... [2] https://github.com/aliceml/aliceml

I dabbled with AliceML a long time ago and it was fun!

But I think Rossberg has since moved on, and his latest attempt at a "better ML design" should be 1ML[0].

[0] https://github.com/rossberg/1ml

Re: Standard ML in 2020

#74

Post by Munksgaard »

eatonphil wrote: post #11
jez wrote: post #10

Which SML implementation has the best editor tooling? The article mentions that certain SML implementations have seen better support for parallel and concurrent programming than OCaml, but Merlin and ocamlformat for OCaml are great as far IDE tooling go. Which SML implementation has the best tooling for things like go to definition, reveal type at cursor, and format file?

None of them have invested very much in tooling as far as I know. There are some small sml-modes for emacs or plugins for vim but they only do basic syntax highlighting. One of the biggest missing things for SML tooling is parsers for SML written in SML. They tend to be written in the implementation language and not exposed as a library. So you don't see SML formatters or documentation generators so much. There have…

MLKit is a (quite performant) SML implementation written in Standard ML, including the parser.

Re: Standard ML in 2020

#76

Post by dllthomas »

EE84M3i wrote: post #67
elihu wrote: post #55

Earlier quoted context omitted.

> Are you familiar with unsafe IO? > It's used pervasively in low-level code because the idealism of monads just doesn't cut it. In my opinion, this proves that the pragmatism of side effects is a necessary evil for actually getting things done in a performant way. It seems like you aren't very familiar with the ways Haskell programmers deal with side effects and mutation. UnsafePerformIo is sometimes needed, and the…

Wait, I thought that lazy io (e.g. getting a lazy string back from "reading" a file, which triggers subsequent reads when you access it) was widely considered bad and a mistake.

This depends very much on the context. Using something like `readFile` without carefully exhausting it is absolutely a mistake in a long lived application or a high volume web server, and in a setting like that reaching for that kind of an interface and hoping future modifications preserve the "reads to exhaustion in reasonable time" is questionable at best.

On the other hand, in a program that handles a small number of files and doesn't live long after file access anyway (say a small script to do grab a couple things, crunch a few numbers, and throw the result at pandoc), there's nothing wrong with lazy IO and it can be quite convenient.

Re: Standard ML in 2020

#77

Post by Munksgaard »

brmgb wrote: post #43
wilsonthewhale wrote: post #18

As someone reasonably versed in OCaml but knows nothing about SML, what are primary differences? Given that OCaml has much better tooling and more of a community, what draws people to SML still?

SML is standardized which is useful if you want to build an implementation for academic purpose. I don't think anyone seriously uses it outside academia however.

I have worked professionally with Standard ML for a few years, but my friends and I used to joke that I was probably the only professional Standard ML developer in existence.

Re: Standard ML in 2020

#78

Post by zwaps »

nine_k wrote: post #58
stutonk wrote: post #34

Earlier quoted context omitted.

The profusion of Category-theoric abstractions and some of the more recent purely functional norms in Haskell are like the PhD-level version of `AbstractVisitorContextFactoryBuilder` which, aside from all the unnecessary cognitive load, lead to enormous dependency graphs of the npm variety. Personally, I wonder if uniqueness types in languages like the sadly forgotten Clean (a close relative of Haskell) would have be…

I don't think there's a way to not use monads, because a ton of everyday things just work in a monadic way, things like lists, or statement sequences in presence of exceptions. I think it's wiser to admit and use these properties instead of ignoring them. Ignoring maths that underlie computation when writing software is like ignoring math that underlies mechanics when building houses: for some time you can get by, bu…

As a bit of an aside, it's interesting that the CS (Haskell, mainly) descriptions of a Monad are much more complicated than the math.

Knowing a little bit of maths, but not much category theory, the wiki entry for Monads(Category Theory) is pretty clear. First sentence: A Monad is an endofunctor (a functor mapping a category to itself), together with two natural transformations required to fulfill certain coherence conditions. Easy.

Knowing a bit of programming, but not much Haskell, reading the entry for Monad (functional programming) or any blog post titled "A Monad is like a ...", it almost seems as if the author is more confused about what a Monad is than me. The first sentences of the Wikipedia article for example are a word-salad. With dressing.

From an outsider's perspective, it's almost as if a monad in functional programming is not a 1:1 translation of the straightforward definition of category theory, leading to an overall sense of confusion.

Re: Standard ML in 2020

#79

Post by sword_smith »

It was the first language that was taught in computer science at the University of Copenhagen until around 2015, then they changed that language to F#/

Judging from the activity on Stack Exchange, it seems to be pretty dead. Maybe a few universities around the world still teach it? It can't be more than I handful I guess. https://stackoverflow.com/tags/sml/topusers

Re: Standard ML in 2020

#80

Post by maattdd »

hajile wrote: post #63
red2awn wrote: post #60

I am designing a language based on OCaml/Standard ML, what are some of the problems present in these languages that can be fixed by a new design without being constrained by a spec or backwards compatibility?

Avoid Ocaml's syntax soup. I'd also avoid making it easy to bolt on a bunch of syntactic extensions ala camlp4 Keep your standard library standard. Module Typeclasses One, immutable string type. Make it UTF-32 by default (you can always store in a smaller format behind the scenes and extend). Make it multiline. Allow variable interpolation (typeclasses should help). SML structural typing and anonymous records are bet…

Anonymous record in SML is equivalent to polymorphic record in OCaml ? (basically, "structural" record)
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