Siraaj Khandkar xandkar

Notes on Riak at Riot Games talk

http://www.infoq.com/presentations/riak-game-scale

Data model challenges (14:25 - 25:00)
- Complex queries - 2i
- Conflict resolution
  - Redundant results for processing same data multiple time - LWW
  - Append-only data, like logs - set union of entries
aggregate stats, sets of counters - no way to resolve conflicts as is.

Is there a user-noticeable difference in how exceptions behave in SML vs OCaml?

Here're a couple of examples demonstrating the generative semantics of SML exceptions (derived from http://mlton.org/GenerativeException) followed by their analogues in OCaml:

	rq = read.table("~/Downloads/request_times.txt", header=FALSE)$V1

	run_simulation = function(router_mode = "naive", reqs_per_minute = 9000, simulation_length_in_minutes = 5, dyno_count = 100) {
	if(!(router_mode %in% c("naive", "intelligent"))) {
	return("router_mode must be one of 'naive' or 'intelligent'")
	}

	reqs_per_ms = reqs_per_minute / 60000
	simulation_length_in_ms = simulation_length_in_minutes * 60000

	# you can make a text file of request times (in ms, one number per line) and import it here, or you can use a probability distribution to simulate request times (see below where setting req_durations_in_ms)
	# rq = read.table("~/Downloads/request_times.txt", header=FALSE)$V1

	# argument notes:
	# parallel_router_count is only relevant if router_mode is set to "intelligent"
	# choice_of_two, power_of_two, and unicorn_workers_per_dyno are only relevant if router_mode is set to "naive"
	# you can only select one of choice_of_two, power_of_two, and unicorn_workers_per_dyno

	run_simulation = function(router_mode = "naive",
	reqs_per_minute = 9000,

	run_simulation = function(router_mode = "naive",
	reqs_per_minute = 9000,
	simulation_length_in_minutes = 5,
	dyno_count = 100,
	choice_of_two = FALSE,
	power_of_two = FALSE,
	unicorn_workers_per_dyno = 0,
	track_dyno_queues = FALSE) {

	if(!(router_mode %in% c("naive", "intelligent"))) {

	module StateSpace :
	sig
	val enumerate : 'a list list -> 'a list list

	val count : 'a list list -> int

	val tests : unit -> unit
	end = struct
	open Printf

	module type LANG =
	sig
	type 'a t

	val eval : 'a t -> 'a
	end

	module L1 : LANG =
	struct
	type _ t =

	$ python [17:44:25]
	Python 2.7.5 (default, Jun 7 2013, 12:41:17)
	[GCC 4.2.1 Compatible Apple LLVM 4.2 (clang-425.0.27)] on darwin
	Type "help", "copyright", "credits" or "license" for more information.
	>>>
	>>> [x for x in range(1, 3)]
	[1, 2]
	>>>
	>>> x
	2

	$ ocaml
	# List.map (fun x -> let rec f x = match x with 0 -> 1 \| n -> n * f (n - 1) in f x) [1; 2; 3];;
	- : int list = [1; 2; 6]
	#
	let rec f x = match x with 0 -> 1 \| n -> n * f (n - 1);;
	val f : int -> int = <fun>
	#
	List.map f [1; 2; 3];;
	- : int list = [1; 2; 6]
	#

	let print_line =
	let line = String.make 80 '-' in
	fun () -> print_endline line

	module UglyA =
	struct
	open Printf

	let x = 5;;

Siraaj Khandkar xandkar

Notes on Riak at Riot Games talk

Is there a user-noticeable difference in how exceptions behave in SML vs OCaml?

1 in SML