Yes, this is right except that the language as written is eager Scheme. You don't need a lazy system. The second and third arguments to If are nullary procedure

Yes, this is right except that the language as written is eager Scheme. You don't need a lazy system. The second and third arguments to If are nullary procedures. Their effects are delayed until invoked by whichever of True or False is supplied. Scheme's notation for invoking a nullary procedure -- `(t)`, vs `t` which just refers to the procedure -- doesn't help matters here :-)