davidrupp

(def thing 1) ; value of thing is now 1
; do some stuff with thing
(alter-var-root #'thing (constantly nil)) ; value of thing is now nil

davidrupp

(def thing 1)
; do some stuff with thing
(def thing nil)
; value of thing is now nil

davidrupp

(def thing 1)

; general form is 
; (alter-var-root var-to-be-altered 
;                 function-to-apply-to-old-value)
(alter-var-root #'thing inc) ; value of thing is now 2
; equivalently ...
(alter-var-root #'thing (fn [old-val] (inc old-val))) ; value of thing is now 3
; also equivalently ...
(alter-var-root #'thing #(inc %1)) ; value of thing is now 4

davidrupp

(def thing 1)
(alter-var-root #'thing (fn [old-val] nil)) ; value of thing is now nil
; we don't really need to name the argument, because we don't use it
; but we *do* need to include it; otherwise we'll get an arity exception
(alter-var-root #'thing (fn [_] nil)) ; value of thing is now nil
; equivalently (kind of) ...
(alter-var-root #'thing (constantly nil))

davidrupp

(#(identity %3) 1 2)
;=> ArityException Wrong number of args (2) passed to: user/eval3407/fn--3408 ...

davidrupp

(def thing 1)

; these all happen to work, but ... yuck
(alter-var-root #'thing #(if %1 nil))
(alter-var-root #'thing #(last [%1 nil]))
(alter-var-root #'thing #(do %1 nil))

davidrupp

Keybase proof

I hereby claim:

• I am davidrupp on github.
• I am davidrupp (https://keybase.io/davidrupp) on keybase.
• I have a public key whose fingerprint is 99A3 E112 A4A4 96D1 64BB EB79 8D5F F86E 49D8 E7C5

To claim this, I am signing this object:

davidrupp

seconds = 356521

days, hours, minutes, seconds = 
  [1.day, 1.hour, 1.minute, 1.second].inject([]) do |acc, unit|
    quotient, seconds = seconds.divmod unit
    acc << quotient
  end

davidrupp

#!/usr/bin/env ruby

require 'find'

Find.find("/Users/david/Developer") do |path|
  Dir.chdir(path) do |d| 
    next unless File.exists? ("#{d}/.git")
    puts d
    `git pull` 
    Find.prune

davidrupp

#!/usr/bin/env ruby

if ARGV.empty?
  puts "Usage: gemmate <name-of-gem>"
else
  src     = `gem which #{ARGV[0]}`.split.last
  lib_dir = src.slice 0, src.rindex("lib")
  `mate -a '#{lib_dir}'`
end