let form binds variables whose names are known
at compile-time. The
cl-progv form provides an easy way to
bind variables whose names are computed at run-time.
This form establishes
let-style variable bindings on a
set of variables computed at run-time. The expressions
symbols and values are evaluated, and must return lists
of symbols and values, respectively. The symbols are bound to the
corresponding values for the duration of the body forms.
If values is shorter than symbols, the last few symbols
are bound to
If symbols is shorter than values, the excess values