[cm3]

This wasn't one of the question of the survey, but while having the right crowd around, I have to ask.

When will Rust get

1. function head patterns like other languages in the ML family, although Rust isn't really part of the family, but rather a distant cousin from another continent, which once played with ML and family during a summer vacation

2. support for naturally writing recursive functions

[Manishearth]

> Rust isn't really part of the family, but rather a distant cousin from another continent, which once played with ML and family during a summer vacation

It's actually more of a sibling in the family who ran away from home at the age of 6 and fell in with the crowd on the wrong side of the tracks.

Initially Rust was very much like ocaml. It isn't anymore :) Many of the normally-in-functional-languages features in Rust come from these days. Others were lost and re-added later. It's a very complex history.

> function head patterns like other languages in the ML family

could you elaborate? I'm not familiar with this feature (only have dabbled in sml).

> support for naturally writing recursive functions

yeah, I wish we had TCO.

[cm3]

> It's actually more of a sibling in the family who ran away from home at the age of 6 and fell in with the crowd on the wrong side of the tracks.

> Initially Rust was very much like ocaml. It isn't anymore :) Many of the normally-in-functional-languages features in Rust come from these days. Others were lost and re-added later. It's a very complex history.

Yeah, having tried Rust in those days, I kinda stopped when it broke every week, and was then surprised with the surface of 1.0. It seemed like a different person to talk to.

I've made my peace with the C'ification of Rust as the price to pay for attracting a large crowd of developers who grew up with C, C++, C#, Java, JavaScript, Ruby, Python, the list goes on. It's a reasonable sacrifice to make, but the two mentioned basic features aren't complex things to wish for.

> could you elaborate? I'm not familiar with this feature (only have dabbled in sml).

Imagine being able to hoist your match clauses into function head (signature?).

  oldEnoughToDrink :: Int -> Boolean
  oldEnoughToDrink 21 -> True
  oldEnoughToDrink _  -> False

Not all languages with support for that force you to repeat the function name, and there are good arguments for/against. For example in Erlang, when you define an anonymous function, you do not repeat it:

  OldEnough = fun(21) -> true;
                 (_)  -> false
              end,

Now, this may seem like a stupid little feature, but trust me when I say it's a natural feature to use like recursive functions after you're used to it.

[cm3]

I should add 3, Erlang's bit syntax, which would be a perfect and natural fit for the target of Rust code. It's a very natural DSL to parse or build (complex) bit streams. You don't necessarily have to add bit syntax comprehensions.

[steveklabnik]

Can you elaborate on what #2 means to you?

[cm3]

We are discouraged from writing recursive functions, which comes naturally when expressing many algorithms. Missing TCO is one cited reason to avoid it, so I gather we're not supposed to, generally speaking.