It's an "eval closure", not an "eval thunk." A thunk is a

It's an "eval closure", not an "eval thunk."  A thunk is a
function of no arguments.
* boot-9.scm (module-type): Rename module field.
(make-module, eval-in-module, make-root-module,
set-current-module): Uses changed.
(module-eval-closure, set-module-eval-closure!,
root-module-closure): Renamed from module-eval-thunk,
set-module-eval-thunk!, root-module-thunk.
(set-current-module): Change uses of *top-level-lookup-thunk* to
*top-level-eval-closure*.