Below is the solution to the small-step evaluation problem involving
functions from the end of the Thu Feb 02 class.

A few notes:

* Lots of people were missing parens. Each lambda expression is
  bounded by a pair of parens that is distinct from the pair of parens
  for the application of that lambda expression to arguments.

* A lambda acts like a "black box", and the details of its body are
  never examined until the box is "opened" when it is applied. In
  particular, the n within (λ (num) (<= num n)) is hidden until this
  lambda expression is applied to a number.

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env3 = n -> 10, small? -> (λ (num) (<= num n)) , sqr -> (λ (n) (* n n))

( {small?} ( sqr n ) ) # env3

=> ( (λ (num) (<= num n)) ( {sqr} n ) ) # env3 [varref for small?]

=> ( (λ (num) (<= num n)) ( (λ (n) (* n n)) {n} ) ) # env3 [varref for sqr]

=> ( (λ (num) (<= num n)) {( (λ (n) (* n n)) 10 )} ) # env3 [varref for n]

=> ( (λ (num) (<= num n)) {(* 10 10)} ) # env3 [apply]

=> {( (λ (num) (<= num n)) 100 )} # env3 [multiplication]

=> (<= 100 {n}) # env3 [apply]

=> {(<= 100 10)} # env3 [varref for n]

=> #f # env3 [less-than-or-equal-to]