[Types-sig] recursive types, type safety, and flow analysis

[Paul Prescod]

Greg Stein wrote:
> 
> I'm talking about figuring out types from the assignments, not from
> declarations. That's it. Forget declarations and the clutter that they
> bring to programs.

Okay, let's try again.

a.py:

a=5

if something():
	a = 5
elif somethingElse():
	a = "abc"
elif somethingElse2():
	a = 32L
elif somethingElse3():
	a = ["ab"]
else:
	del a


b.py:

import a
a.a = "jab"

c.py:

import a
a.a = ("abc",5)

d.py:

import a, b, c

j: Int
j = a.a

What's the error message? What are the list of valid types that a.a
could have at this point and how would the type system have inferred
them?

 Paul Prescod