> Haskell is a research language; Rust is designed to be a practical language. It makes a lot of concessions to practicality, C-like syntax and imperative control flow being high among them.
Perhaps I wasn't clear in the post you're responding to: my point was that both Rust and Haskell are fairly "simple" programming languages which seem more complicated, because they introduce a lot of features which are likely to be new to those who are using it for the first time. I wasn't really comparing them as languages per se; that's a separate discussion.
> Common in any language, including Go.
Higher-order functions are common in most languages, but not in the way that Haskell does. Most languages use first-class functions as lists of instructions (do some stuff, and perform the steps in this argument). Haskell makes them truly first-class, such that they're positively ubiquitous: an example is currying, which is everywhere in Haskell and rare in most other languages; another example is monads, which are obviously a core part of Haskell and which require first-class functions (e.g. in >>=) to do anything useful. There are other examples.
> Rust does not have these.
I know; I was speaking about Haskell.
> This is because we want memory safety without performance tradeoffs (global concurrent garbage collection).
Right; it's a perfectly understandable thing to have, but it's not something that (to my knowledge) exists in any other mainstream language. It's an example of something in Rust which is obscure to newcomers.
> Could you elaborate?
I'd have to write some code and run the compiler to get the actual error message, but I recall getting errors about using some reference outside of a context or something. In my fuzzy recollection, it would be something like where I had written `match foo { a => b; c => d}` and I would get some error message which would be fixed by writing `let foo1 = foo; match foo1 {a => b; c => d}`. Unfortunately I don't remember the specifics, but long story short: compiling Rust code produces a lot of very strange error messages to someone unfamiliar with the language. :) In this way it's not dissimilar from Haskell.
> This is because dynamically-sized types are not yet implemented, but they will be for 1.0.
Great to know! If only there were a more helpful error message than "Bare str is not a type." :)
> In my fuzzy recollection, it would be something like where I had written `match foo { a => b; c => d}` and I would get some error message which would be fixed by writing `let foo1 = foo; match foo1 {a => b; c => d}`. Unfortunately I don't remember the specifics, but long story short: compiling Rust code produces a lot of very strange error messages to someone unfamiliar with the language.
Ah, sounds like you were using a value after it the destructor on it ran, which was fixed by moving it to a separate variable (so that the destructor ran later). This kind of error is familiar to C++ programmers, so I wouldn't say it's unique to Rust, although it's a runtime error (actually, undefined behavior) in C++ and not in Rust. A good static analysis package for C++ would emit the same error that the Rust compiler did.
Yeah that's probably right. And yes for sure I'm not only talking about things which are unique to these languages, but just things for which there might be large groups of users who are not familiar with them. Similarly, users of ML (or category theoreticians) are going to be less confused by many of Haskell's idiosyncrasies. :)
Perhaps I wasn't clear in the post you're responding to: my point was that both Rust and Haskell are fairly "simple" programming languages which seem more complicated, because they introduce a lot of features which are likely to be new to those who are using it for the first time. I wasn't really comparing them as languages per se; that's a separate discussion.
> Common in any language, including Go.
Higher-order functions are common in most languages, but not in the way that Haskell does. Most languages use first-class functions as lists of instructions (do some stuff, and perform the steps in this argument). Haskell makes them truly first-class, such that they're positively ubiquitous: an example is currying, which is everywhere in Haskell and rare in most other languages; another example is monads, which are obviously a core part of Haskell and which require first-class functions (e.g. in >>=) to do anything useful. There are other examples.
> Rust does not have these.
I know; I was speaking about Haskell.
> This is because we want memory safety without performance tradeoffs (global concurrent garbage collection).
Right; it's a perfectly understandable thing to have, but it's not something that (to my knowledge) exists in any other mainstream language. It's an example of something in Rust which is obscure to newcomers.
> Could you elaborate?
I'd have to write some code and run the compiler to get the actual error message, but I recall getting errors about using some reference outside of a context or something. In my fuzzy recollection, it would be something like where I had written `match foo { a => b; c => d}` and I would get some error message which would be fixed by writing `let foo1 = foo; match foo1 {a => b; c => d}`. Unfortunately I don't remember the specifics, but long story short: compiling Rust code produces a lot of very strange error messages to someone unfamiliar with the language. :) In this way it's not dissimilar from Haskell.
> This is because dynamically-sized types are not yet implemented, but they will be for 1.0.
Great to know! If only there were a more helpful error message than "Bare str is not a type." :)