[bitc-dev] Benton/Kennedy try/let

[Jonathan S. Shapiro]

First, a syntax question: should we distinguish this with a keyword,
or simply extend the existing syntax of LET? That is, should it be:

  TRY <binding>
  IN body-expr
  catch e1 => expr
  ...
  catch eN => expr
  otherwise => expr

or simply

  LET <binding>
  IN body-expr
  [ catch e1 => expr
    ...
    catch eN => expr
    otherwise => expr ]

One issue here is: if we adopt the LET version, then LET probably
can't allow multiple bindings in a single LET form. Perhaps that can
be resolved, but SML and Haskell people don't seem to find that
burdensome.

There is one thing that I do find strange about this construct: the
scope of the try block is the binding, not the body expression.