consistently use do lambda

[krux02]

This change makes consistent use of the do notation. The no notation is an official syntax for lambda expressions. Without the do the code relies on implicit conversions of statement list to a callback lambda expression. As mentioned in my earlier PR, this feature is flaky.

[iffy]

If it's at all possible to keep, I love the current terse syntax. Could something be done within argparse to allow users to not have to use do?

For instance, could argparse do the same thing nimscript does for tasks? https://github.com/nim-lang/Nim/blob/master/lib/system/nimscript.nim#L331 Does that avoid flakiness?

[krux02]

well, currently command is written as a proc that takes a procedure argument as the last argument. In this situation you need a lambda expression. Nim has many different syntaxes for this. Here are they:

import sugar

proc command*(name: string, group: string, content: proc()) =
  content()

command "a","b", proc() =
  echo 1
  echo 2
  echo 3

command("a","b", proc() =
  echo 1
  echo 2
  echo 3
)

command("a","b") do:
  echo 1
  echo 2
  echo 3

command("a","b", () => (echo 1; echo 2; echo 3))

From all these options I still think the do notation is the most compact. But for that API you need to pick one lambda syntax.

An alternative would be to make command into a template. You can pass a block of code to a template that isn't a lambda and you can instantiate it as many times as you want. No do: required.

[krux02]

My PR to mainline Nim is blocked by this PR. Is there anything preventing this PR from being merged?

Here is the error message:
https://ci.appveyor.com/project/dom96/nim/builds/27155600/job/kdrac67cvypbmjkt/tests

[iffy]

Sorry for the delay! Just busy with life and job.

I was hoping to see if I could switch to a template to keep the more terse syntax. Let me see if I can do it quickly, otherwise, I'll merge this one in.

[iffy]

Fixed in v0.8.3. Thank you so taking the time to explain do:!