fogus

Arities as pseudo-protocol

Recently the Clojure team released an alpha version of the core.async library that includes a new library named Flow. While the new functionality is amazing and is already inspiring devs to use it, this post is not about Flow. Instead, I'd like to talk about a small part of the Flow API where process behavior is implemented in terms of step-fns. Simply put, step-fns are functions of four arities, where each arity is called at key points in the life-cycle of a process to provide configuration information or perform behaviors.

The four arities are as follows:

0. Describe the step-fn by returning a data-structure describing its boundaries
1. Returns the initialization state for the enclosing process given compatible arguments
2. Called every time a life-cycle transition occurs with a state and transition key and returns an updated state
3. Called in a loop for every mes

fogus

;                          Stumbling towards Y
;
; The applicative-order Y combinator is a function that allows one
; to create a recursive function without using define.
; This may seem strange. Usually a recursive function has to call
; itself, and thus relies on itself having been defined.
;
; Regardless, here we will stumble towards the implementation of the
; Y combinator (in Scheme).

fogus

(defn range-3d6
  "A function to return the possible rolls with 3d6 between start and end inclusive."
  ([n] (list n))
  ([start end]
   (for [d100s (range 1 7)
         d10s (range 1 7)
         d1s  (range 1 7)
         :let [num (+ (* 100 d100s) (* 10 d10s) d1s)]
         :when (and (<= start num) (<= num end))]
     num)))

fogus

  :async-259
  (System/setProperty "clojure.core.async.go-checking" "true")
  (Boolean/getBoolean "clojure.core.async.go-checking")

  (require '[clojure.core.async :as async])
  (require '[clojure.core.async.impl.dispatch :as d])

  @#'clojure.core.async.impl.go/go-checking

  (let [c (async/chan 1)]

fogus

A
B
C
D
E
F
G
H
I
J

fogus

(ns fogus.vthreads
  (:require [clojure.core.async :as ca]))

(set! *warn-on-reflection* true)

ca/io-thread-exec

(let [c (ca/chan)]
  (ca/io-thread (ca/>!! c "hello"))
  (assert (= "hello" (ca/<!! (ca/io-thread (ca/<!! c)))))

fogus

@book {Arbib-Manes:75,
    AUTHOR = "Arbib, M. and Manes, L.",
    TITLE = "Arrows, Structures and Functors:
             The Categorical Imperative",
    NOTE = "Home library",
    PUBLISHER = "Academic Press",
    YEAR = 1975}
@incollection{Backus-etal:90,
    AUTHOR = "J.W. Backus and J. Williams and E.W. Wimmers",
    TITLE = "An Introduction to the programming Language {FL}",

fogus

;; testing task impl on dev-vthreads branch
;; requires JDK 21+ 

(ns c.c.async
  (:require [clojure.core.async :as ca]))

(set! *warn-on-reflection* true)

(let [c (ca/chan)]
  (ca/task (ca/>!! c "hello"))

fogus

# this forces Arena into full screen mode on startup, set back to 3 to reset
# note that if you go into the Arena "Graphics" preference panel, it will reset all of these
# and you will need to run these commands again
defaults write com.wizards.mtga "Screenmanager Fullscreen mode" -integer 0
defaults write com.wizards.mtga "Screenmanager Resolution Use Native" -integer 0

# you can also replace the long complicated integer bit with any other scaled 16:9
# resolution your system supports.
# to find the scaled resolutions, go to System Preferences --> Display and then
# divide the width by 16 and multiple by 9. on my personal system this ends up

fogus