Confused about metaprogramming: macros

I have started to use Metaprogramming now. While my code is running, I noticed that there are some things that I do not understand. My understanding is that at the simplest level macros return an expression which is then evaluated. So, I tried to define a variable b and set its value to one using a macro:

macro test(x)
quote
b=1
end
end

When I then run in REPL:

b

Then I get an error message:

ERROR: UndefVarError: b not defined

The macro seems to return 1.

On the other hand if I type,

eval(Meta.parse(“b=1”))

Then b is defined in the REPL.

I would have expected the macro and the eval call to have the same effect. Apparently, there is something I am not understanding here…

Thanks!

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