[FR] Trailing closure syntax

[rdje]

NGS supports Closures.

But it doesn't seem to have support for the so called trailing closure syntax.

It is when calling a function and the last argument of that function is a closure, one may pop it out of the function's parentheses and have it dangling outside of it after the closing parenthesis of the function, like this

1. funcname(..., closure) <=> funcname(...) closure
2. funcname(closure) <=> funcname() closure <=> funcname closure

When dangling outside of the function's argument list, the closure has the following form

{ code }

Ruby, Groovy, Kotlin, Swift and Raku support this syntactic sugar feature.

• Is there any even remote plan to support trailing closure syntax ?
• Will you be even interested to have NGS support the trailing closure syntax ?

[ilyash-b]

But it doesn't seem to have support for the so called trailing closure syntax.

The Problem

I am thinking about this from time to time and don't know how to solve syntactic ambiguity that this would cause:

if CONDITION YES_BODY NO_BODY, for example: if 1 my_func() { A + 1 }. Is {A + 1} the NO_BODY here or last argument to my_func().

Closest Thing

NGS has a way to supply arguments after the my_func() parenthesis using with or do syntax:

test("my test") with { ... }
my_func(1,2) do { ... }

• with and do are repeatable so you can my_func() do { ... } do { ...}
• with and do can be followed by anything, not just closure: my_func() with 1 with 2 with { ... }

Thoughts

• Having both with and do for the same functionality is very likely a mistake
• Repeated with and do have roughly zero observed real use cases.
• Using with and do not with closures also have roughly zero observed real use cases.
• Trailing closure syntax does make the syntax a bit cleaner.
• I find myself using with and do less and less over time.
• As the time passes by I'm having more doubts that the additional syntax is worth it.

[rdje]

Ok then, it seems you already had this trailing closure syntax feature in mind for some time now.

So feel free to close my FR then.

[ilyash-b]

Let's break our heads on that if/when there is more demand.