lethain

module Main (main) where

minOrZero lst = if null lst then 0 else minimum lst
coins 0 _ = 0
coins v ds = (1 + minOrZero [coins (v - d) ds | d <- ds, (v - d) >= 0])

main = do print "start"
          print (coins 57 [1, 5, 10, 25])
          print (coins 15 [1, 6, 9, 10])

lethain

module Main (main) where

col :: Int -> [Int] -> [Int]
col 1 acc = acc
col n acc | n `mod` 2 == 0 = col (n `div` 2) (n:acc)
          | otherwise  = col (3 * n + 1) (n:acc)

opts :: Int -> [(Int, Int)]
opts n = [(length(col x []), x) | x <- [1..n]]

lethain

# using ruby_parser from https://github.com/seattlerb/ruby_parser
# also ruby2ruby for convert sexps to ruby code: sudo gem install ruby2ruby
require 'ruby_parser'
require 'ruby2ruby'

def load
  txt = ''
  while line = gets
    txt += line
  end

lethain

# Caveat that picking "year one" is kind of arbitrary, and that these
# are just random numbers from the internet, not meant as canonical sources

Year  Google  Facebook  Twitter  Uber
1     11      7         8	
2     60      15        29	
3     284     150       130      60
4     682     450       350      170
5     1628    850       833      1000
6     3021    1218      2712

lethain

Description

Migrations are both essential and frustratingly frequent as your codebase ages and your business grows: most tools and processes only support about one order of magnitude of growth before becoming ineffective, so rapid growth makes them a way of life.

Two of Stripe’s most important migrations have been typing our Ruby codebase and migrating our metrics and dashboard stack. This talk will explore why migrations are the only mechanism to effectively manage technical debt as your company and code grows, what makes running them so hard, and a repeatable approach to running them effectively:

lethain

Successful CFP submission by Lita Cho, included in this list

Service Mesh in Kubernetes: it’s not that easy

KubeCon 2019

In this talk, presenters will share lessons from several years of experience running Envoy in production at scale. They will explore practical techniques for triaging issues in a service mesh, along with the intuition behind them. The presenters will cover a broad range of topics including traffic capture, issues specific to GRPC, health checks, and techniques useful during incident mitigation. The talk will end with a deep dive into Envoy stats and their use in resolving issues.

Envoy 2019

lethain

Short description

Learn how Stripe has evolved their approach to prioritizing infrastructure as they grew from two founders to 1,300+ employees and millions of users.

Long description

Deciding what to work on is always difficult, and is especially treacherous for folks working as infrastructure engineers and leaders. Infrastructure teams that solve the right problems subtlety shift their company's trajectory upwards. Poor approaches lead toward a morass of