fib.funk

; Returns a lambda, which for each invocation gives the next Fibbonnaci number
fib := { a := 0
         b := 1
         { n := a
           c := a + b
           a = b
           b = c
           n } }

seq := fib:

seq:
; => 0
seq:
; => 1
seq:
; => 1
seq:
; => 2
seq:
; => 3
seq:
; => 5
seq:
; => 8
seq:
; => 13

; .. etc