scratch.myr

(pi "The constant pi") 3.14 def

(area-of-disk
  "Calculate the area of a cirlce disk."
  (radius -- area))
(dup * pi *)
defn

(area-of-ring
  "Calculate the area of a ring."
  (outer inner -- area))
(area-of-disk swap area-of-disk swap -)
defn

(area-of-triangle
  "Calculate the area of a triangle."
  (base height -- area))
(* 2 /)
defn

(area-of-rectangle
  "Calculate the area of a rectangle."
  (side-a side-b -- area))
(*)
defn

(factorial (n -- n-fac)
  "Calculate the factorial of n.")
(dup 0 =
  (drop 1)
  (dup dec factorial *)
  if)
defn

(fib (n -- nth-fib))
(dup 0 =
  (drop 0)
  (dup 1 =
    (drop 1)
    (dup dec fib swap dec dec fib +)
    if)
  if)
defn

(fib (n -- nth-fib))
(dup 0 = if
  (drop 0)
  (dup 1 = if
    (drop 1)
    (dup dec fib swap dec dec fib +)))
defn

(fib (n -- nth-fib))
(cond
  ((dup 0 =) (drop 0)
   (dup 1 =) (drop 1)
   (true)    (dup dec fib swap dec dec fib)))

(fib (n -- nth-fib))
(((dup 0 =) (drop 0)
  (dup 1 =) (drop 1)
  (true)    (dup dec fib swap dec dec fib +))
 cond)
defn


Variants
- Special evaluation
  - Immediate data, or
  - Lists are not evaluated (like Smalltalk code blocks)
- Words, invoke function or push value
  - symbols invoke functions, keywords pushes values
- Function/block stack contract
  - fixed numer of pops, fixed number of pushes