From eb0ca097aa0ab568c9e47f8446fd77494fd1b03c Mon Sep 17 00:00:00 2001
From: Reid D McKenzie <me@arrdem.com>
Date: Sun, 24 May 2020 01:22:43 -0600
Subject: [PATCH]

---
 README.md | 97 ++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 78 insertions(+), 19 deletions(-)

diff --git a/README.md b/README.md
index b1a7ed4..a1ee8ea 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,8 @@
 # Flowmetal
 
-> That of which servitors are made
+> A shining mercurial metal laden with sensors and almost infinitely reconfigurable.
+>
+> The stuff of which robots and servitors are made.
 
 Flowmetal is a substrate for automation.
 It attempts to provide a programming environment wherein programs are durable, evented and asynchronous aimed at what would traditionally be described as scripting or coordination.
@@ -68,19 +70,64 @@ In this setup, the Flowmetal interpreters are able to interact with an external
 For instance this program would use the external connector stubs to build up interaction(s) with an external system.
 
 ```lisp
+(defpackage flowmetal.time
+  (defenum time-unit
+    "Calendar-independent durations."
+    +milliseconds+
+    +seconds+
+    +hours+
+    +days+)
+
+  (defrecord duration [num : int?, scale : time-unit?]
+     "A type for representing scalar durations.")
+
+  (defn as-milliseconds [d : duration?]
+                        : duration?
+     "Normalize a duration to a number of milliseconds."
+     (match d
+        [(duration x +days+)         (duration (* x 24) +hours+)]
+        [(duration x +hours+)        (duration (* x 60) +minutes+)]
+        [(duration x +minutes+)      (duration (* x 60) +seconds+)]
+        [(duration x +seconds+)      (duration (* x 1000) +milliseconds+)]
+        [(duration x +milliseconds+) d]))
+
+  ;; A type of one value used to represent an error
+  (defenum timeout
+    +timeout+)
+    
+  (defendpoint with-timeout!
+     [d : duration?
+      f : (fn? [] : a)]
+     : a
+
+    )
+
+)
 
 (defpackage com.twitter.wilson
   (require
     ;; The log lets you record status information into a program's trace
-    [flowmetal.log :refer [log]]
+    [flowmetal.log
+     :refer [log!]]
     ;; The time system lets you put bounds on the implicit awaiting Flowmetal does
-    [flowmetal.time :refer [with-timeout, timeout?, duration, duration?, sleep]]
+    [flowmetal.time
+     :refer [with-timeout!, timeout?, make-duration, duration?, +seconds+, +hours+, sleep!]]
     ;; JSON. Simple enough
-    [flowmetal.json :refer [loads, dumps, json?]]
+    [flowmetal.json
+     :refer [loads, dumps, json?]]
     ;; Extensions! Provided by other systems.
-    ;; These two allow for HTTP requests to be made and callbacks to be received.
-    [http.callback :refer [make-callback, get-callback, callback?]]
-    [http.request  :refer [post, error?, dns-error?, connection-error?, response-error?]])
+    ;;
+    ;; This one allows for an external service to receive HTTP callbacks on Flowmetal's behalf.
+    [http.callback
+     :refer [make-callback!, get-callback!, callback?]]
+     ;; This one allows for an external service to make HTTP requests on Flowmetal's behalf.
+    [http.request
+     :refer [post!, error?, dns-error?, connection-error?, response-error?]])
+
+  (defenum stage
+    +reboot+
+    +bios-update+
+    +reinstall+)
 
   ;; FIXME: how to do table optimization?
   (defn fib [x]
@@ -89,11 +136,18 @@ For instance this program would use the external connector stubs to build up int
        [1 1]
        [_ (+ (fib (- x 1) (- x 2)))]))
 
-  (defn retry-http [f :- (fn [] :- a)
-                    backoff-fn :- (fn [int?] :- duration?) :default (fn [x] (duration (fib x) :seconds))
-                    backoff-count :- int? :default 0]
-                    :- a
-    """The implementation of HTTP retrying."""
+  (defn retry-http [f
+                      : (fn? [] a?)
+                    backoff-fn
+                      : (fn? [int?] duration?)
+                      :default (fn [x : int?]
+                                   : duration?
+                                  (make-duration (fib x) +seconds+))
+                    backoff-count
+                      : int?
+                      :default 0]
+                    : a
+    """The implementation of HTTP with retrying."""
     (let [response (f)]
       (if (not (error? response))
          response
@@ -104,16 +158,20 @@ For instance this program would use the external connector stubs to build up int
              (do (sleep (backoff-fn backoff-count))
                  (retry-http* f backoff-fn (+ backoff-count 1)))))))
 
-  (defn job [hostname :- str,
-             stages :- (list? str?),
-             job-timeout :- duration? :default (duration 3 :hours)]
-             :- (union timeout? json?)
+  (defn job [hostname
+               : str?
+             stages
+               : (list? stage?)
+             job-timeout
+               : duration?
+               :default (duration 3 :hours)]
+             : (union? [timeout? json?])
     """Run a wilson job, wait for the callback and process the result.
 
     By default the job is only waited for three hours.
 
     """
-    (let [callback :- callback? (make-callback)
+    (let [callback : callback? (make-callback!)
           job (retry-http
                 (fn []
                   (post "http://wilson.local.twitter.com"
@@ -123,8 +181,9 @@ For instance this program would use the external connector stubs to build up int
                       :stages [stages]
                       :callbacks [{:type :http, :url callback}]}))))]
 
-      (let [result (with-timeout (duration 3 :hours)
-                     (get-callback callback))]
+      (let [result (with-timeout! (duration 3 :hours)
+                     (fn []
+                        (get-callback callback)))]
          (if-not (timeout? result)
            (loads result)
            result))))