actually capture partial continuations
* libguile/control.c (cont_objcode): Along with a bunch of boilerplate
that certainly needs to go in some central place, define this
continuation-calling trampoline.
(reify_partial_continuation): New function, returns a procedure that
when called will reinstate a partial continuation.
(scm_c_abort): Take an extra arg, the cookie. Actually reify a
continuation.
(scm_at_abort): Adapt to scm_c_abort change.
* libguile/control.h: Declare scm_c_abort change.
* libguile/vm-i-system.c (partial_cont_call): New instruction.
(call/cc, tail-call/cc): Adapt to scm_i_vm_capture_stack change.
(abort): Pass vm_cookie to abort.
* libguile/vm.h (SCM_F_VM_CONT_PARTIAL, SCM_F_VM_CONT_REWINDABLE): New
flags.
(struct scm_vm_cont): Add flags field.
(SCM_VM_CONT_PARTIAL_P, SCM_VM_CONT_REWINDABLE_P): New predicates.
* libguile/vm.c (scm_i_vm_capture_stack): Rename from
vm_capture_continuation, and make internal instead of static. Take a
flags argument.
(scm_i_vm_capture_continuation): Adapt to scm_i_vm_capture_stack
change.
(vm_abort): Plumb cookie to scm_c_abort.
(vm_reinstate_partial_continuation): New stub.