incompatibilities

See additions for incompatibilities caused by additional features.

behavior

• = to a variable declares it on the current scope. Use := to modify ones on upper scopes.
• ===/!==/==/!= each compiles as is.
• super represents the direct reference to the parent function rather than being a call itself. Use super ... (just super in Coffee) for full delegation.
• Nested comprehensions return flattened results.
• Within non-triple-quoted strings (''/""), indentations after newlines are ignored altogether.
• do does not specialcase function literals. Use let instead.
• \ does not introduce a pseudo block. It simply cancels following whitespaces.

keyword

• The roles of in and of have been swapped to keep the JS semantics.
• yes/ no / on / off are unreserved. Define your own or just use true/false.
• switch-case-default replaces switch- when -else.
• for ever replaces loop.
• is not replaces isnt.
• void replaces undefined.
• ~> (wavy arrow) replaces => (fat arrow).
• when is removed. Use a if b while c instead of a while c when b.
• it/that/fallthrough are semi-reserved. They get special meanings depending on context.
• eval/arguments are keywords as per ES5.

grammar

• () is always a call; allowing f (), disallowing () ->.
• ... is prefix as per harmony:spread.
• and/or and spaced ./?. close implicit calls. f a .g b or h c means f(a).g(b) || h(c).
• The range syntax ( x..y ) is removed.
• Block comment is /* */ rather than ### ### .
• Heregex is // // rather than /// ///.
• No implicit call against blocks starting with an implicit object. Use do instead:

array.push do
	a: 1
	b: 2

• a-b desugars to aB instead of a - b
• "#variable" === '' + variable instead of "#variable" === '#variable'
• in a class constructor, omit constructor:.

other

• CLIs are named coco and coke (to coexist with coffee and cake).
• JavaScriptLint support is removed (for being pointless).