1.3.1 - Coffeescript

releaseHeader('2012-04-10', '1.3.1', '1.2.0')

CoffeeScript now enforces all of JavaScript’s Strict Mode early syntax errors at compile time. This includes old-style octal literals, duplicate property names in object literals, duplicate parameters in a function definition, deleting naked variables, setting the value of eval or arguments, and more. See a full discussion at #1547.
The REPL now has a handy new multi-line mode for entering large blocks of code. It’s useful when copy-and-pasting examples into the REPL. Enter multi-line mode with Ctrl-V. You may also now pipe input directly into the REPL.
CoffeeScript now prints a Generated by CoffeeScript VERSION header at the top of each compiled file.
Conditional assignment of previously undefined variables a or= b is now considered a syntax error.
A tweak to the semantics of do, which can now be used to more easily simulate a namespace: do (x = 1, y = 2) -> …
Loop indices are now mutable within a loop iteration, and immutable between them.
Both endpoints of a slice are now allowed to be omitted for consistency, effectively creating a shallow copy of the list.
Additional tweaks and improvements to coffee --watch under Node’s “new” file watching API. Watch will now beep by default if you introduce a syntax error into a watched script. We also now ignore hidden directories by default when watching recursively.