* `#t` is true and `#f` is false
* `(lambda () ...)` constructs a thunk
+ * there is no difference in meaning between `[...]` and `(...)`; we just sometimes use the square brackets for clarity
* `'(1 . 2)` and `(cons 1 2)` are pairs (the same pair)
* `(list)` and `'()` both evaluate to the empty list
* `(null? lst)` tests whether `lst` is the empty list