% cs217d13.dl

let x = 5 in x

% Ex 3.5.11, p 82

let a = 1
in let a = 3
   in let p = proc (x) +(x, a)
          a = 5
      in *(a, (p 2))

% Ex 3.5.12, p 82 -- recursion works with dynamic binding

let fact = proc (n) add1(n)
in
  let fact = proc (n)
               if zero?(n)
               then 1
               else *(n, (fact sub1(n)))
  in
    (fact 5)

% Ex 5.5.13, p 82

let a = 1 in
  let a = 3
      p = proc () a
  in let f = proc (x) (p)
         a = 5
     in (f 2)

let a = 1 in
  let a = 3
      p = proc () a
  in let f = proc (a) (p)
         a = 5
     in (f 2)


% makemult, p 80

let makemult = proc (maker, x)
                if zero?(x)
                then 0
                else +(4, (maker maker sub1(x)))
in
  let times4 = proc (x) (makemult makemult x)
  in
    (times4 3)

% Abstracting the body of the intended recursive function

let
  e = proc (f, x)
        if zero?(x)
        then 0
        else +(4, (f sub1(x)))
in
  let
    fm = proc (m, x)
          (e 
            proc(x) (m m x)
            x)
  in
    let f = proc (x) (fm fm x)
    in
      (f 3)


% Ex 3.5.3, p 80


% factorial

let
  e = proc (f, x)
        if zero?(x)
        then 1
        else *(x, (f sub1(x)))
in
  let
    fm = proc (m, x)
          (e 
            proc(x) (m m x)
            x)
  in
    let f = proc (x) (fm fm x)
    in
      (f 5)