Sample Orc DSL for Common Lisp

orc-sample.lsp

; examples from http://orc.csres.utexas.edu/tryorc.shtml#tryorc/tutorial/

; site definition, similar to a function but handles network transparency and will publish multiple values if you call them   
; multiple times
; they will necessarily hide much magic

(defsite name (arg)
  (body ...))

; I may consider using plain-old functions for this but at the moment I might need to hide some magic

; parallel site calls
; sites are prefixed with `site-`
; site-prompt is analogous to the Prompt site on the Orc demo page that returns user input
(par [(site-prompt "Spoon or fork?")
      (site-prompt "Bowl or saucer?")]) ; both responses are theoretically retrieved, though we do nothing with them

; sequential - the result of the first site call could be bound to x and used as an arg for the second
(seq (x)
  (site-prompt "What was the last movie that you saw?")
  (site-prompt "Was it good?"))

; parallel sequential - write will be called twice as each parallel computation returns
(seq (movie)
  (par [(site-prompt "Pick a movie you like: ")
        (site-prompt "Pick a movie you like: ")])
  (write-line "I heard that %s was a good movie" movie))

; pruning - return the first value produced by a site computation; write will only happen once here
; imagine a write function which takes a value and writes it to the screen
; also note that what par returns behaves like a site so pruning is very useful when combined with par
(write
  (prune
    (par [(site-prompt "Apples or oranges?")
          (site-prompt "Grapes or mangos?")])))

; parallel pruning - "red" and "blue" will be written immediately, and the middle computation will wait
(par [(write "red")
      (write 
        (concat "light"
          (prune (site-prompt "Choose a color: "))))
      (write "blue")])