Unix System Programming with Standard ML (2001) [pdf]

http://www.mlton.org/References.attachments/Shipman02.pdf

by vector_spaces • 6 years ago

142 47 6 years ago

mhd3• 6 years ago

Note that despite the origin of the link the book seems to use SML/NJ, not MLTon.

brudgers3• 6 years ago

Nothing against MLTon, but SML/NJ seems to be in more common use based on my experience with the [SML] tag on StackOverflow.

mhd3• 6 years ago

Definitely. That's why I got excited and thought that there's something specific about MLTon that's used for systems programming here (the capabilities of the "Standard" MLs vary a bit).

saityi3• 6 years ago

I like to use SML/NJ for development and experimentation, and MLton for final compilation.

SML/NJ is a really nice development environment, and using a different compiler like MLton or Poly/ML for the final compilation forces you to use the more common, standard subset of ML rather than implementation-specific features.

voidhorse• 6 years ago

Standard ML is almost the perfect language—functional-first without all the heavyweight and seemingly endlessly proliferating categorical abstractions which keeps the level of knowledege one needs to be productive low. Plus it’s easy to drop into old school imperative code when needed.

The only thing holdong sml back in my eyes is somewhat clunky syntax and the module system—which is great at first but quickly becomes tricky once you start having to use functors.

A modern, reimagined sml that keeps its core while adopting some of the nicer syntactic improvements from other langs in the family and improving the module system would be a god send

mhd3• 6 years ago

Isn't the simplicity of SML one of its strengths, even Ocaml being more complex?

If you're going for more sugar, F# might fit the bill. Can handle shebangs, too.

brudgers3• 6 years ago

If you like SML, it might be worth trying Erlang. It comes out of a telecom company, too. The mechanical sympathy I love in SML, I find in Erlang. The ideas that seeded SML, seem to have have found more fertile ground at Ericsson where they still thrive. YMMV.

akavel• 6 years ago

Erlang has dynamic typing, no? Static typing is especially what interests me in SML, and it's a such core thing, I'm kinda honestly confused what's similar between SML and Erlang?? (I don't know either of them well, so I'd be really interested to learn about some deep similarities from experienced people.)

the_af2• 6 years ago

Out of curiosity, what did you find clunky about the syntax? I think languages in the ML family have quite simple and minimal syntax.

saityi3• 6 years ago

The only thing I find clunky about SML syntax are infix operators, since fixity specifications aren't exported.

http://mlton.org/InfixingOperators

Otherwise, I love SML syntax, and would be curious to see the answer to this, too. I find it refreshingly simple and consistent. Is it that it uses 'let ... in ... end' and such rather than whitespace or brackets?

oconnor0• 6 years ago

What's the problem with the module system and functors?

chriswarbo4• 6 years ago

SML modules are a classic example of a "shadow language" ( https://gbracha.blogspot.com/2014/09/a-domain-of-shadows.htm... ). I'd like to see an ML-like language where modules/interfaces are normal values, functors are just normal functions, etc.

Modeling such a system at the value level is easy enough, but having it run at compile-time introduces some tricky issues (especially around IO).

cannam• 6 years ago

Andreas Rossberg's 1ML is (was?) an effort to unify the module syntax with that of functions and values (https://people.mpi-sws.org/~rossberg/papers/Rossberg%20-%201..., https://github.com/rossberg/1ml)

The module syntax is certainly clumsy in comparison to the rest of the language, and it's not just the syntax - everything about functor arguments is a bit murky.

saityi3• 6 years ago

Scala is interesting in this sense; I'd consider it to be an ML-like language. It attempts to unify object systems and module systems, and they are fairly first class in Scala. Modules (objects) can be used as normal values; you can encode functors as functions or classes as needed; signatures (traits) are usable as values to some degree, too.

Furthermore, path-dependent types allow Scala to unify modules and objects, so that the same language constructs can be used to specify the overall structure of a program as well as its implementation details. The unification of the module and term languages is witnessed by the following comparison with the ML module system: Scala objects correspond to ML modules, classes to functors, and interfaces to signatures [Odersky and Zenger 2005].

https://arxiv.org/pdf/1904.07298.pdf

proaralyst• 6 years ago

OCaml has first-class modules & functors (functions on modules). I can write something like:

  let f (type t) some_arg (module M : Stringable with type t = t) = M.to_string some_arg

This will have the type signature

  val f : 'a -> (module Stringable with type t = 'a) -> string

In this case the module type Stringable looks like:

  module type Stringable = sig
    type t
    val to_string : t -> string

Functors are just module types so can be used in the same way. Module types fit in as normal values, you don't have to pattern match on them. This works:

  let id x = x
  
  id (module Int)

mumblemumble• 6 years ago

The only thing holdong sml back in my eyes is somewhat clunky syntax and the module system

Those are both tricky, but I think the much bigger deal is that the package ecosystem is about as lush as the parts of Antarctica that are above sea level.

I suspect that the standard getting whacked together before the language really had a chance to mature had the unfortunate effect of stunting its growth.

int_19h• 6 years ago

Compared to OCaml, SML pattern matching syntax can be frustrating, mainly because there's no guards. It's not needed that often - but when it's needed, the code with guards is much simpler than multiple branches with nested conditionals.

gmfawcett2• 6 years ago

A similar, nicely written book for Ocaml:

https://ocaml.github.io/ocamlunix/

jerry403• 6 years ago

Few years ago I took a course by prof. Dan Grossman on Coursera, there was a part about SML and I so liked it (the language and the course). Now I want to read Okasaki's "Purely Functional Data Structures" book and try to reproduce the code examples in SML.

the_af2• 6 years ago

Programming Languages by Dan Grossman, I took it too. Pretty good course, and a nice intro to static typing and FP with SML. Also nice: the DrRacket part, I wasn't familiar with lisp/scheme-like languages. Also also nice: how you can tell he doesn't really like Ruby ;)

jerry403• 6 years ago

Oh yes, and I can remember the episode when he jumped while explaining some idea in order to make this moment unforgettable. Shame on me, I forgot what idea it was but still remember his jumps :)

yawaramin2• 6 years ago

As far as I remember PFDS is actually written with SML code.

jerry403• 6 years ago

Somehow I have an impression that I tried something and could not repeat it in SML/NJ. I can recall it was about streams and lazy evaluations, but now I think that I just misused Lazy lib since I haven't used SML for a while. So this is getting easier, great, thanks! :)

lwb2• 6 years ago

As someone with absolutely zero experience with ML languages of any kind, would this be the best intro for me to get into it? Or would I be better off with OCaml?

wbl• 6 years ago

The Little Mler if you like elephants and food.

Koshkin2• 6 years ago

The focus on food was very distracting, I remember.

nextos• 6 years ago

Try https://www.cs.tufts.edu/comp/105-2019s/readings/tofte-tips.... and then https://www.cl.cam.ac.uk/~lp15/MLbook/

gmfawcett2• 6 years ago

Eventually I would learn Ocaml, as it's the more sensible language for most production code (community, tooling, ecosystem, etc.). But there's nothing wrong with learning SML first. 90% of what you learn will be transferable to Ocaml. Starting with SML might help you focus on the "essence" of ML languages rather than getting overwhelmed by the impressive range of options that Ocaml opens up.

The MLton implementation of SML -- while not necessarily the best ML to practice on -- is particularly interesting because it's a whole-program optimizing compiler. It has a reputation for producing very compact, efficient machine code. Having said that, Ocaml is still a comparatively simple language -- compared to say, Haskell or C++ -- and its native compiler is well known for turning out decent and very predictable code (predictable in the sense that you can read some source code and have a decent understanding of what kind of machine code it will get compiled into).

If you decide to learn Ocaml first, but want to stick to "essential ML", I would recommend Jason Hickey's "Introduction to Ocaml" [1] over the more modern "Real World Ocaml" [2], as the latter book introduces every bell and whistle that Ocaml offers, and has a much more ecosystem-dependent focus (third party libraries, third party tooling, etc.). Still a fine book, but I think it emphasizes advanced Ocaml features a bit too much for an introductory text.

[1] http://courses.cms.caltech.edu/cs134/cs134b/book.pdf [2] https://realworldocaml.org/

lwb2• 6 years ago

Great comment, I'll bookmark those!

manno23• 6 years ago

Honestly the book Purely Functional Data Structures opened my eyes to the different approach functional languages supply. The concept of pattern matching is so pervasive in ML and I would say that in tandem with creating data structures using types is the central idea of ML that you put to use when using it.

madhadron• 6 years ago

I think that Ullman's 'Elements of Standard ML' remains one of the best introductions to functional programming in general. Wonderful little book...

yawaramin2• 6 years ago

Start with this: https://www.coursera.org/learn/programming-languages

Free online course that teaches statically-typed functional programming using SML as a teaching language. Lecture videos are short and to the point. Prof. Dan Grossman is widely recognized as a great lecturer and he gets the ideas across really well.

From there learn OCaml, which is the ML with the widest industry adoption.

sigzero• 6 years ago

If you want to learn a bit and check out OCaml.

https://try.ocamlpro.com/

_sbrk• 6 years ago

Ah, Standard ML. That brings back great memories of my compiler class at University. This was the first functional language that I was truly comfortable with, and a great tool to write our toy compiler.

Unix System Programming with Standard ML (2001) [pdf]

Related Stories