strip_imp

boolSyntax.strip_imp : term -> term list * term

Iteratively breaks apart implications.

If M is of the form t1 ==> (... (tn ==> t) ...), then strip_imp M returns ([t1,...,tn],t). Note that

   strip_imp(list_mk_imp([t1,...,tn],t))

will not return ([t1,...,tn],t) if t is an implication.

Failure

Never fails.

Example

> strip_imp "(T ==> F) ==> (T ==> F)";;
Exception- Type error in function application.
   Function: strip_imp : term -> term list * term
   Argument: "(T ==> F) ==> (T ==> F)" : string
   Reason:
      Can't unify term (*Created from opaque signature*) with
         string (*In Basis*) (Different type constructors)
Fail "Static Errors" raised

> strip_imp (Term `t1 ==> t2 ==> t3 ==> ~t`);
val it = ([“t1”, “t2”, “t3”, “t”], “F”): term list * term

See also

boolSyntax.list_mk_imp, boolSyntax.dest_imp