[olavk]

It is somewhat unfair to compare this to Python, since a lot of the simplicity in Python comes from the semantics (dynamically typed, garbage collected and so on). Rust need to express all this information (types, lifetimes etc.), so it will necessarily be more dense. The question is if this information could be expressed in a more readable syntax. This might be possible, but I would like to see a suggestion of how.

I guess the signature could be made more readable by using a few type aliases. The hardest part to read is the nested types.

I'm with you on the macro syntax, it is very hard to read. It is not easy to create a readable macro syntax though. All languages I know have hard-to-read macros, so this is not yet a solved problem.

[iopq]

Here is a simpler syntax:

   fn accumulate tuples: &[(&'a Str, &Fn(i32) -> Bool)], i: i32 -> t
   where
        t: Monoid + From &'a Str + From String,

this is how Haskell with lifetimes and borrowing would look like (if arguments were not curried)

[Rusky]

This is arguably less readable, because it's missing some delimiters for your eyes to latch onto.

It's also not realistically parseable- the Haskell/Ocaml-like removal of <>s and ()s relies on application being left-associative, and if you read this under that rule you've changed the meaning (e.g. `From &'a Str`).

[olavk]

I like removing superfluous punctuation, but if parentheses are removed from method signatures than they should also be removed from invocations, which in turn comes with its own set of readability issues. I'm not a fan of the $ operator in Haskell, for example.

[antaviana]

This also reminds me that, in Python 2.x, the following code...

for i in range(100000000):

...creates in memory a list with one-hundred million integers.

Expressive yes, but sometimes it can be double-edged for new comers (and not new comers).