So this is just a dumb little post regarding syntax.

I’ve been pairing with a colleague who is new to Elixir lately and today we were briefly discussing how do/end is really syntactic sugar that essentially gets converted into a keyword list as [{:do, block}] and gets passed as the last argument to whatever is calling it. I was showing them how—while fairly useless—it even works with regular functions (not just macros) and I was creating modules with a single function in IEx to demonstrate. Afterwards this got me thinking if the following syntax would work:

foo = fn args ->
  args[:do]
end

foo.() do
  "bar"
end

Lo-and-behold it does!

Again, this is pretty useless in practice (and many of you are likely thinking “Sure, why wouldn’t that work?”) but it slightly expanded my own understanding of the ast/sugar ergonomics. Mostly I just thought it was cool and I’m home alone on a Friday night and I had to tell someone

If anyone has a better/different/(or even worse) way that they describe how do/end works, please feel free to share.

…and actually, are there practical uses of do/end for plain function functions I’m not thinking of?