Generator in Retro

gistfile1.txt

( generator )
{{
  : xt,   ( - ) 1 , @last @d->xt , ;
---reveal---
  : yield ( - ) 1 , here 5 + , xt, ` :is 9 , xt,  ` :devector ; compile-only
}}

: foo   ( - ) "State one" puts yield
              "State two" puts yield
              "State three" puts ;

: ...  ( - n )
  [[ here 0 , ]] repeat [[ 1 , , ]] [ @ 1 ] sip +! yield again ;

( private variables )
: A @last 4 - .data ; compile-only
: B @last 3 - .data ; compile-only
: C @last 2 - .data ; compile-only
: D @last 1 - .data ; compile-only

: withPrivate: ( parse:"name" - ) 4 allot : ;

withPrivate: ...  ( - n )
  0 !A repeat A [ @ 1 ] sip +! yield again ;


( fib sequence, iterative, with private variables + yield )
withPrivate: fib ( - n )
  1 !A 0 !B 0 yield 1 yield repeat @A @B + @A !B dup !A yield again ;