dest_var
Term.dest_var : term -> string * hol_type
Breaks apart a variable into name and type.
If M is a HOL variable, then dest_var M returns (v,ty), where v
is the name of the variable, an ty is its type.
Failure
Fails if M is not a variable.
See also
Term.mk_var, Term.is_var,
Term.dest_const,
Term.dest_comb, Term.dest_abs