Not sure about $ but I sometimes miss the |> operator (which takes the
value from the left and inserts it as the 1st argument of the function call
to the right).
foo(a, b) |> bar(c, d) |> baz(e, f)
== baz(bar(foo(a, b), c, d), e, f)
This allows for easier "functional" decompsition of chains of operations. I
found it to be very useful when writing Elixir; in Rust there's the OO-like
traits which may make it less useful - it still might be worthwhile for
people writing more functional code.
On Wed, Sep 25, 2013 at 9:40 PM, Marvin Löbel <loebel.mar...@gmail.com>wrote:
> We don't use the symbol in our syntax, but are using functional paradigm
> that sometimes result in a bit hard to read nested calls.
>
> I'd propose that it works similar to `do`, in that it allows to move the
> last expression of an function or method call after the parentheses, though
> they would still remain required for ambiguity reasons:
>
> ~~~
> a(b(c(1,d(2,3,4,e()))))
> == a() $ b() $ c(1) $ d(2,3,4) $ e()
>
> let v: ~[uint] = from_iter() $ range(0, 100);
> ~~~
>
> In that sense, it wouldn't really be an operator but syntactic sugar for a
> function call.
> It might even be possible to replace `do` with it, though the now required
> parentheses would make it longer:
>
> ~~~
> do task::spawn { ... }
> task::spawn() $ || { ... }
> ~~~
>
> Downside is of course that it adds another symbol, which could alienate
> more potentiall users, and it could mean a shift-away-from or at least an
> inconsistency-with methods and method chaining in general.
>
> Which would be ironic because I wanted it in some complicated Iterator
> chain. ;)
>
> It could of course always be implemented as a syntax extension, and in any
> case I don't expect this to get any attention before Rust 2.0. :)
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