Function types syntax

[Neal Gafter]

This variation on John Rose's proposed syntax has no problematic
interaction with arrays:

  #(String -> float throws IOException)

This could be paired with the existing lambda syntax, or use the
matching lambda syntax

  #(String s)->1.2

or even drop the # and write a lambda this way

  (String s)->1.2

One could also leave the result type first, and move the throws clause
into the parens of the function type

  #float(String throws IOException)

I think any of these are more readable than the current function type syntax

  #float(String)(throws IOException)

Finally, if we take a page from the Groovy playbook, a lambda would be written

  {String s -> 1.2}

I think the most natural corresponding notation for a function type would be

  {String -> float throws IOException}

I know the latter work out syntactically without ambiguity, because
that's been implemented in BGGA (but with a fat arrow instead of a
thin arrow).  I don't know how they'd interact with collection
literals.

Cheers,
Neal