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Discussion on: Why I love Ruby: almost everything is a call

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Replies for: Talking about intuitiveness, don't know why Proc is treated differently in Crystal. Other languages treats function pointers as normal functions an...

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Ary Borenszweig •

This is the same in Ruby too. The main reason is that you can invoke methods without parentheses. Let's say you have this:

def foo
  ->{ 1 }
end
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And suppose we could invoke a Proc just by using parentheses, like a regular method invocation. So it would be like this:

f = foo # this returns the Proc
f() # this would in theory invoke it
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But then there are some ambiguities with the above... The main one is this:

f = foo() # does this return the Proc and executes it, or it just returns the proc?
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Another ambiguity is what happens if there's an f method in the same scope:

def f
  2
end

f = foo
f() # Does this call the `f` Proc, or the `f` method?
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If we decide it calls the method, then if f didn't exist and it now exists (someone added it after we wrote those two lines), the meaning would change. If we decide it calls the f Proc, then all foo_bar() calls must be treated like assuming they are procs, if there's a foo_bar local variable in the current scope. But maybe once the language was popular they thought about doing that but it would be a huge breaking change. It's very common to have local variables and methods be named the same in Ruby.

In Crystal we made it the same as in Ruby. I actually think having a call method simplifies things: you can be sure what you have is a Proc. Also procs in Crystal aren't used that much...