melee-roguelite/lib/stdio.fnl

(require "love.event")
(local view (require "lib.fennelview"))

;; This module exists in order to expose stdio over a channel so that it
;; can be used in a non-blocking way from another thread.

(local (event channel) ...)

(when channel
  (let [prompt (fn [next-line?] (io.write (if next-line? ".." ">> ")) (io.flush) (.. (io.read) "\n"))]
    ((fn looper [input]
       (when input
         ;; This is consumed by love.handlers[event]
         (love.event.push event input)
         (let [output (: channel :demand)
               next-line (and (. output 2) (= "next-line" (. output 2)))]
           ;; There is probably a more efficient way of determining an error
           (if next-line :ok
               (and (. output 2) (= "Error:" (. output 2)))
               (print (view output))
               (each [_ ret (ipairs output)]
                 (print ret)))
           (io.flush)
           (looper (prompt next-line))))) (prompt))))

{:start (fn start-repl []
          (let [code (love.filesystem.read "lib/stdio.fnl")
                luac (if code
                         (love.filesystem.newFileData
                          (fennel.compileString code) "io")
                         (love.filesystem.read "lib/stdio.lua"))
                thread (love.thread.newThread luac)
                io-channel (love.thread.newChannel)
                coro (coroutine.create fennel.repl)
                out (fn [val]
                      (: io-channel :push  val))
                options {:readChunk (fn [parser-state]
                                      (when (> parser-state.stack-size 0)
                                        (: io-channel :push  ["next-line" "next-line"]))
                                      (coroutine.yield))
                         :onValues out
                         :onError (fn [kind ...] (out [kind "Error:" ...]))
                         :pp view
                         :moduleName "lib.fennel"}]
            ;; this thread will send "eval" events for us to consume:
            (coroutine.resume coro options)
            (: thread :start "eval" io-channel)
            (set love.handlers.eval
                 (fn [input]
                   (coroutine.resume coro  input)))))}