Although Rust heavily borrows from the ML family, the fact it has mutability and imperative reasoning makes it hard to compare them.
But if you want a short one:
- Sum Types EDIT: AND Product Types (silly me)
- function-objects & closures
- typeclasses (as far as I can tell), but no higher kinded types
- no monads, functors nor monoids built-in
- trait objects (eg. runtime polymorphism, think "abstract classes")
I don't think Rust is that much different from other functional languages. The main critical difference is the manual memory management feature - the way it's acknowledged and used throughout the language and the ecosystem means that the functional patterns commonly used in garbage collected languages don't look nearly as natural in Rust.
Maybe I'm missing something, but aren't tuples and structs/records examples of product types? Which both rust and haskell have?
Rust most certainly has them, as does Haskell. Records/structs of course are just the same thing with names for the components.
Thus, even Java has product types.
Even C has product types. Which is why I'm always bothered when people claim language X lacks algebraic data types.
They probably lack sum types, but are very unlikely to lack product types.
That makes no sense. Algebraic data types are not expressed, they're a concrete thing, a classification of composite types (by multiplication (hence product types) or addition (hence sum types)).
Some shitty languages don't have a concise way for you to express particular things (like sum types), so you have to rely on idioms or "patterns".
{ 1 = "hi", 2 = "howdy" };
val it = ("hi","howdy") : string * string