Shedskin Python

Shedskin is another experimental Python compiler. Previously I tested Psyco, a Just-in-Time Python compiler which operates while the program is running. Shedskin is a more traditional compiler, run in separate steps beforehand. Shedskin actually generates templated C++ code, which is then compiled with GCC.

Since Python is dynamically typed while C++ is statically typed, Shedskin performs type inference over your program. It generates C++ templates to support parametrically polymorphic functions. A simple example, previously used in my article Types and Programming Languages:

  def palindrome(x, y):
    return (x, y, x)
 
  print palindrome(1, 2)
  print palindrome("a", "b")

Results:

  (1, 2, 1)
  ('a', 'b', 'a')

With shedskin, the following C++ template is generated:

  template <class A> tuple2<A, A> *palindrome(A x, A y) {
      return (new tuple2<A, A>(3, x, y, x));
  }

and used:

  str *const_0, *const_1;
  const_0 = new str("a");
  const_1 = new str("b");
  print("%s\n", palindrome(1, 2));
  print("%s\n", palindrome(const_0, const_1));

While support for many Python constructs and library functions is currently limited, Shedskin was able to compile unmodified the same Ant-Colony-Optimization Python code I had used previously with Psyco Python. It is significantly faster, coming within 3x the performance of the baseline C version:

                    Time   Multiple   
                 in secs       of C   
C                    0.4          1
Shedskin Python      1.2          3
Psyco Python         5.5         14
Python              40.0        100