Comprehension syntax

Questions & Help Questions
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8

Well, no. It is still consistent behaviour among all other calls:

quote do
  foo bar: 1, do: 10
end
# => {:foo, [], [[bar: 1, do: 10]]}

quote do
  foo bar: 1 do
    10
  end
end
# => {:foo, [], [[bar: 1], [do: 10]]}

There are 2 reasons why for is special form and not “regular” macro:

  • Compiler need to know that it is comprehension, so it can output Erlang comprehension as well
  • <<a <- binary>> syntax need special handling
  • Macros do not support variable arguments list (the same rules as any other call apply there as well)

So all of the above forces the Elixir to treat for as a “special thing” within parser itself.