~~~
{{
  'FID var

  :write-byte (n-)  @FID file:write ;
  :mask       (n-)  #255 and ;

  :write-cell (n-)
           dup mask write-byte
    #8 shift dup mask write-byte
    #8 shift dup mask write-byte
    #8 shift     mask write-byte ;
---reveal---
  :image:save (s-)
    file:open-for-writing !FID
    #0 here [ fetch-next write-cell ] times drop
    @FID file:close ;
}}

'retro.nga image:save
~~~