Python's use of indentation for scoping is problematic because:

  1. It prevents the use of multi-statement lambdas.
  2. It prevents writing many useful command line filters (a la perl -e '...', ruby -e '...', awk '...', etc.)
  3. It prevents embedding python within a text document (similar to PHP, Mason, etc.)

Guido von Rossum on designing a new language today .