[MLton] expansive expressions yielding polymorphic values

[Henry Cejtin]

Right,  I  know that clients can't take advantage of it, but I didn't realize
that I (the implementor) could.  Truly a fine surprise.  It really means that
inside  of  a  structure  which implements some phantom type, I can take full
advantage of higher-order functions instead of being  limited  by  the  value
restriction.

Definitely a very pleasant surprise to me.