dest_select
boolSyntax.dest_select : term -> term * term
Breaks apart a choice term into selected variable and body.
If M has the form @v. t then dest_select M returns (v,t).
M
@v. t
dest_select M
(v,t)
Fails if M is not an epsilon-term.
boolSyntax.mk_select, boolSyntax.is_select
boolSyntax.mk_select
boolSyntax.is_select