Gary Fredericks gfredericks

gfredericks / queue.rb

Created November 6, 2013 20:46

Bakers queue impl in rubby just cuz. It's probably broken or terrible.

	class PersistentList
	attr_reader :length, :head, :tail
	include Enumerable
	EMPTY = Object.new
	class << EMPTY
	include Enumerable
	def length; 0; end
	def each(&block); end
	def to_s; "()"; end
	def cons(item); PersistentList.new(item, self); end

gfredericks / with-local-redefs.clj

Last active November 30, 2022 15:30

thread-local version of with-redefs

	(defn with-local-redefs-fn
	[a-var its-new-value func]
	(cast clojure.lang.IFn @a-var)
	(alter-meta! a-var
	(fn [m]
	(if (::scope-count m)
	(update-in m [::scope-count] inc)
	(assoc m
	::scope-count 1
	::thread-local-var (doto (clojure.lang.Var/create @a-var)

gfredericks / primes_via_addition.clj

Last active December 22, 2015 06:29

A lazy primes function in Clojure using only addition and comparisons.

	(defn primes
	"Returns a lazy sequence of primes."
	[]
	(cons 2
	(lazy-seq
	(let [local-primes (->> (primes)
	(map (juxt identity #(apply + (repeat % %)))))]
	(->> (iterate #(+ % 2) 3)
	(remove (fn [n]
	(->> local-primes

gfredericks / defring.clj

Last active December 22, 2015 02:49

abstract algebra helpers

gfredericks / slow-deftypes.clj

Created August 28, 2013 15:35

deftype is 6 times slower than vectors?

gfredericks / executor-reflection.clj

Created July 23, 2013 00:06

Reflection with Executor?

	(import '[java.util.concurrent Executors Executor])

	(set! warn-on-reflection true)

	(def ^Executor tp (Executors/newFixedThreadPool 4))

	;; Reflection warning, NO_SOURCE_PATH:1:1 - call to submit can't be resolved.
	(.submit ^Executor tp ^Callable (constantly 42))

gfredericks / postgres-arrays.clj

Created July 22, 2013 19:56

Reading postgres arrays in java.jdbc

	(extend-protocol IReadResult
	java.sql.Array
	(read-result [sqlarray]
	(let [rs (.getResultSet sqlarray)]
	(loop [rows []]
	(if (.next rs)
	(recur (conj rows (.getObject rs 2)))
	rows)))))

gfredericks / usages.clj

Created June 15, 2013 19:38

A Clojure function which, given a filename, returns a map from vars to sets of referenced vars.

	(defn usages
	[filename]
	(let [forms (-> filename
	slurp
	(->> (format "(%s)"))
	read-string)
	analyses (map clojure.tools.analyzer/analyze-form forms)
	defs (filter (comp #{:def} :op) analyses)]
	(into {}
	(for [def defs

gfredericks / bytes->uuid.clj

Last active December 17, 2015 11:29

Converting a byte array to a UUID

	(defn byte->long [b] (if (neg? b) (+ 256 b) b))

	(defn bytes->long
	[bytes]
	{:pre [(= 8 (count bytes))]}
	(apply + (map bit-shift-left (reverse (map byte->long bytes)) (range 0 64 8))))

	(defn bytes->uuid
	[bytes]
	(java.util.UUID. (bytes->long (take 8 bytes))

gfredericks / laser_css.clj

Created April 1, 2013 00:46

css selector in laser

	(let [re-1 #"([^#\.:])((?:[#\.][^#\.:]+))"
	re-2 #"([#\.])([^#\.:]+)"]
	(defn css
	"Laser selector for css stuff. Just handles the AND format
	of foo#bar.baz.bang, no ORing."
	[s]
	(let [[_ a b] (re-matches re-1 (name s))]
	(assert (or (seq a) (seq b)) "Bad css selector.")
	(apply l/and
	(if (empty? a)