[MLton] Exporting closures to C code

[Henry Cejtin]

You want to do much more than that because of the fact that the data in the
environment closed over has to be GC'd.

In general, all of the approaches I have seen to doing this (in mGTk among
others) cause the extra C arg to be an int which is then used to look up the
function (on the ML side) in a table and call it.  I.e., the code part of the
call back is always to the same function and only the `environment' part tells
you which MLton closure you are going to call.