Daniel Díaz Carrete danidiaz

What I Wish I'd Known About Equity Before Joining A Unicorn

Disclaimer: This piece is written anonymously. The names of a few particular companies are mentioned, but as common examples only.

This is a short write-up on things that I wish I'd known and considered before joining a private company (aka startup, aka unicorn in some cases). I'm not trying to make the case that you should never join a private company, but the power imbalance between founder and employee is extreme, and that potential candidates would

How to mount a VirtualBox shared folder when the Guest OS boots

Problem

While using VirtualBox's Guest Additions to mount shared folders provides a seamless way to mount shared folders, there are also disadvantages.

Shared folders will always mount in /media/sf_(share name) unless specified using through vbox drivers in the guest OS
Mounting does not happen at boot-time. Applications that require paths at boot will not be able to access the shared folder even after it is mounted - such as Docker.

Solution

Instead of relying on Guest Additions, if you have sudo permissions, shared folders can be mounted at boot-time using fstab. Using this approach allows

Moved to https://github.com/kbilsted/Functional-core-imperative-shell/blob/master/README.md

Advanced Functional Programming with Scala - Notes

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

Applied Functional Programming with Scala - Notes

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

Edit — February 2019

This gist had a far larger impact than I imagined it would, and apparently people are still finding it, so a quick update:

TC39 is currently moving forward with a slightly different version of TLA, referred to as 'variant B', in which a module with TLA doesn't block sibling execution. This vastly reduces the danger of parallelizable work happening in serial and thereby delaying startup, which was the concern that motivated me to write this gist
In the wild, we're seeing (async main(){...}()) as a substitute for TLA. This completely eliminates the blocking problem (yay!) but it's less powerful, and harder to statically analyse (boo). In other words the lack of TLA is causing real problems
Therefore, a version of TLA that solves the original issue is a valuable addition to the language, and I'm in full support of the current proposal, which you can read here.

I'll leave the rest of this document unedited, for archaeological

Reddit discussion.

Disclaimer 1: Type classes are great but they are not the right tool for every job. Enjoy some balance and balance to your balance.

Disclaimer 2: I should tidy this up but probably won’t.

Disclaimer 3: Yeah called it, better to be realistic.

Type classes are a language of their own, this is an attempt to document features and give a name to them.

	# Count total EBS based storage in AWS
	aws ec2 describe-volumes \| jq "[.Volumes[].Size] \| add"
	# Count total EBS storage with a tag filter
	aws ec2 describe-volumes --filters "Name=tag:Name,Values=CloudEndure Volume qjenc" \| jq "[.Volumes[].Size] \| add"
	# Describe instances concisely
	aws ec2 describe-instances \| jq '[.Reservations \| .[] \| .Instances \| .[] \| {InstanceId: .InstanceId, State: .State, SubnetId: .SubnetId, VpcId: .VpcId, Name: (.Tags[]\|select(.Key=="Name")\|.Value)}]'
	# Wait until $instance_id is running and then immediately stop it again
	aws ec2 wait instance-running --instance-id $instance_id && aws ec2 stop-instances --instance-id $instance_id

	# Get 10th instance in the account

	-- This is a valid PID 1 process in Haskell, intended as a Docker
	-- entrypoint. It will handle reaping orphans and handling TERM and
	-- INT signals. This is a work in progress, please do not use it in
	-- production!

	{-# OPTIONS_GHC -Wall -Werror #-}
	import Control.Concurrent (forkIO, newEmptyMVar, takeMVar, threadDelay,
	tryPutMVar)
	import Control.Exception (assert, catch, throwIO)
	import Control.Monad (forever, void)

	{-# LANGUAGE AllowAmbiguousTypes
	, DataKinds
	, DeriveGeneric
	, DuplicateRecordFields
	, FlexibleContexts
	, FlexibleInstances
	, KindSignatures
	, MultiParamTypeClasses
	, ScopedTypeVariables
	, TypeApplications