How does Ruby 1.9 handle character cases in source code?

Question

In Ruby 1.8 and earlier,

Foo

is a constant (a Class, a Module, or another constant). Whereas

foo

is a variable. The key difference is as follows:

module Foo
  bar = 7
  BAZ = 8
end

Foo::BAZ
# => 8

Foo::bar
# NoMethodError: undefined method 'bar' for Foo:Module

That's all well and good, but Ruby 1.9 allows UTF-8 source code. So is ℃ "uppercase" or "lowecase" as far as this is concerned? What about ⊂ (strict subset) or Ɖfoo?

Is there a general rule?

Later:

Ruby-core is already considering some of the mathematical operators. For example

module Kernel
  def √(num)
    ...
  end
  def ∑(*args)
    ...
  end
end

would allow

x = √2
y = ∑(1, 45, ...)

I would love to see

my_proc = λ { |...| ... }

x ∈ my_enumerable  # same as my_enumerable.include?(x)

my_infinite_range = (1..∞)

return 'foo' if x ≠ y

2.21 ≈ 2.2

Answer 1

I don't know what ruby would do if you used extended UTF8 characters as identifiers in your source code, but I know what I would do, which would be to slap you upside the back of the head and tell you DON'T DO THAT

Answer 2

I would love to see

my_proc = λ { |...| ... }

x ∈ my_enumerable  # same as my_enumerable.include?(x)

my_infinite_range = (1..∞)

return 'foo' if x ≠ y

2.21 ≈ 2.2

I would love to see someone trying to type that program on an English keyboard :P