Swift REPL throws python error?

Question

When I try running the swift REPL using swift or xcrun swift, I get the following Python error:

Hristos-MacBook-Pro:~ Hristo$ swift

Fatal Python error: PyThreadState_Get: no current thread

Abort trap: 6

It looks like Swift's REPL was written in Python. I recently installed pip, which might have broken something. I am using Xcode 6.1 (A1052d) and OS X Yosemite. What could be the case?

Answer 1

I changed the active python version (previously python 2.7 installed via macports) and it worked:

sudo port select python python33

Answer 2

I just ran into the same problem. The above answer gave me a hint for a non-invasive solution (in my case I have fink's python at the head of the path)

% PATH=/usr/bin:$PATH
% swift

This solution is based upon the following observations. Fink (and I presume Macports and possibly other third-party python providers) put their bin directories at the head of the path. This can be seen by invoking python on the command line:

% which python
/sw/bin/python

This is where I ran into the problem that lead me to search for a solution:

% swift
Fatal Python error: PyThreadState_Get: no current thread
[1]    19219 abort      swift

By changing the $PATH variable at the shell level, the problem is avoided without changing the default condition for future shell sessions:

% PATH=/usr/bin:$PATH
% which python
/usr/bin/python

So now it works:

% swift
Welcome to Swift!  Type :help for assistance.
   1>

A more permanent solution (short of permanently changing the order of the $PATH variable elements) might be to include in one's shell dotfile the following alias (or equivalent function):

alias swift="PATH=/usr/bin:$PATH swift"