Lin He he9lin

Understanding Comparative Benchmarks

I'm going to do something that I don't normally do, which is to say I'm going to talk about comparative benchmarks. In general, I try to confine performance discussion to absolute metrics as much as possible, or comparisons to other well-defined neutral reference points. This is precisely why Cats Effect's readme mentions a comparison to a fixed thread pool, rather doing comparisons with other asynchronous runtimes like Akka or ZIO. Comparisons in general devolve very quickly into emotional marketing.

But, just once, today we're going to talk about the emotional marketing. In particular, we're going to look at Cats Effect 3 and ZIO 2. Now, for context, as of this writing ZIO 2 has released their first milestone; they have not released a final 2.0 version. This implies straight off the bat that we're comparing apples to oranges a bit, since Cats Effect 3 has been out and in production for months. However, there has been a post going around which cites various compar

Architecture

Use Onion architecture
- Dependencies go inwards. That is, the Core domain doesn't know about outside layers
Use pipeline model to implement workflows/use-cases/stories
- Business logic makes decisions
- IO does storage with minimal logic
- Keep Business logic and IO separate
Keep IO at edges

If you want a run-down of the 1.3 changes and the design decisions behidn those changes, check out the LonestarElixir Phoenix 1.3 keynote: https://www.youtube.com/watch?v=tMO28ar0lW8

To use the new phx.new project generator, you can install the archive with the following command:

$ mix archive.install https://github.com/phoenixframework/archives/raw/master/phx_new.ez

Bump your phoenix dep

Phoenix v1.3.0 is a backwards compatible release with v1.2.x. To upgrade your existing 1.2.x project, simply bump your phoenix dependency in mix.exs:

Change your database RDS instance security group to allow your machine to access it.
- Add your ip to the security group to acces the instance via Postgres.
Make a copy of the database using pg_dump
- $ pg_dump -h <public dns> -U <my username> -f <name of dump file .sql> <name of my database>
- you will be asked for postgressql password.
- a dump file(.sql) will be created
Restore that dump file to your local database.
- but you might need to drop the database and create it first
- $ psql -U <postgresql username> -d <database name> -f <dump file that you want to restore>

the database is restored

Deploying Phoenix on Dokku

Worked 2015-09-08 for Phoenix 1.0.1 on Dokku 0.3.25.

These instructions assume you've set up Dokku. If not, go find a tutorial for that part. My notes for setting it up on Digital Ocean.

On your local machine, in the app's repo

Create a Dokku app:

	(*
	Demonstrates DTO validation for a news feed domain
	*)

	// "result.fsx" comes from https://github.com/swlaschin/DmmfWorkshop/blob/master/src/E-ModelingErrors/Result.fsx
	#load "result.fsx"

	module Domain =
	type DocumentId = DocumentId of int
	type EmailAddress = EmailAddress of string

	module EnvDemo

	open System
	open System.IO

	[<Struct>]
	type Nothing =
	private
	\| Nothing

	-- Our goal is to create a type describing a list of events. This is our
	-- type-level DSL.
	-- We will then use typeclass resolution to "interpret" this type-level DSL
	-- into two things:
	-- 1. A comma-separated list of events
	-- 2. A method that, when given an event name and a payload, will try to parse
	-- that event type with the payload. A form of dynamic dispatching
	--
	-- To model a list of types we will use tuples. You can imagine the list of
	-- types "Int, String, Char" to look like:

	defmodule Randomizer do
	@moduledoc """
	Random string generator module.
	"""

	@doc """
	Generate random string based on the given legth. It is also possible to generate certain type of randomise string using the options below:

	* :all - generate alphanumeric random string
	* :alpha - generate nom-numeric random string

	(*
	ParserLibrary_v1.fsx

	Version 1 of the code for a parser library.

	Related blog post: http://fsharpforfunandprofit.com/posts/understanding-parser-combinators/

	*)

	open System