Sadly http://pasterack.org is currently off-line
In the meantime why not try out the R16 "trick bot"!
It saves snippets of code, which can then be recalled and executed on user-provided input.
Many thanks to the creators:
to get started go to Racket Discord, select the #bots channel and type commands
- 
!rkt helpfor help - 
!!instant-tshirt Racketto make a t-shirt 
e.g.
Docs at R16 -- Community-Driven Interactive Code Evaluation
!rkt eval
(require pict file/convertible racket/draw)
(~>
  (pict->bitmap (standard-fish 250 100))
  (convert 'png-bytes)
  (make-attachment "fish.png" 'image/png))
            