What we really need is for some people to turbocharge ghcjs (http://news.ycombinator.com/item?id=1818820 http://news.ycombinator.com/item?id=1818820), so that w

What we really need is for some people to turbocharge ghcjs (http://news.ycombinator.com/item?id=1818820 http://news.ycombinator.com/item?id=1818820), so that we can get optional static type checking in Javascript. Haskell is great at parsing[1] and great at type checking. So how about it parse the relatively simple JS grammar[2] and do some static checking on JS code? You could augment existing JS code with an optional accepts/return syntax to provide type annotations: foo = function(x) { return [x+1,x+2]} foo.accepts = Numeric foo.returns = [Numeric, Numeric] This is similar to Collin Winter's typecheck for python (http://pypi.python.org/pypi/typecheck/ http://pypi.python.org/pypi/typecheck/), which has some nontrivial bugs but which is conceptually interesting. [1] You could use Matt Might's new derivative parser if you want to have some fun while doing this (he has a Haskell implementation to boot!) http://matt.might.net/articles/parsing-with-derivatives/ http://matt.might.net/articles/parsing-with-derivatives/ [2] Real World Haskell has a good JSON example that should be easily extensible to the full syntax: http://book.realworldhaskell.org/read/writing-a-library-working-with-json-data.html http://book.realworldhaskell.org/read/writing-a-library-work... EDIT: Doctor JS by Mozilla is a (very) good start here -- maybe it already does everything we need... http://doctorjs.org http://doctorjs.org