Patrick (Rick) Pearson pwpearson

10 Scala One Liners to Impress Your Friends

Here are 10 one-liners which show the power of scala programming, impress your friends and woo women; ok, maybe not. However, these one liners are a good set of examples using functional programming and scala syntax you may not be familiar with. I feel there is no better way to learn than to see real examples.

Updated: June 17, 2011 - I'm amazed at the popularity of this post, glad everyone enjoyed it and to see it duplicated across so many languages. I've included some of the suggestions to shorten up some of my scala examples. Some I intentionally left longer as a way for explaining / understanding what the functions were doing, not necessarily to produce the shortest possible code; so I'll include both.

1. Multiple Each Item in a List by 2

The map function takes each element in the list and applies it to the corresponding function. In this example, we take each element and multiply it by 2. This will return a list of equivalent size, compare to o

Typography

Headings

Headings from h1 through h6 are constructed with a # for each level:

# h1 Heading
## h2 Heading
### h3 Heading

PSQL

Magic words:

psql -U postgres

If run with -E flag, it will describe the underlaying queries of the \ commands (cool for learning!).

Most \d commands support additional param of __schema__.name__ and accept wildcards like *.*

Months

SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()) - 1, 0) -- First day of previous month

SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), -1) -- Last Day of previous month

SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0) -- First day of this month

SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()) + 1, -1) -- Last day of this month

###Mount HFS & HFSPLUS (Apple Filesystem Types)

First thing first, you have to install kmod-hfs & kmod-hfsplus and hfsplus-tools.

Step 1: Import GPG Key

rpm --import http://elrepo.org/RPM-GPG-KEY-elrepo.org

To install ELRepo for CentOS-7:

	-- Find more at http://iterm.sourceforge.net/scripting.shtml

	launch "iTerm"

	tell application "iTerm"
	activate

	-- ssh in split panes to my varnish stack
	set myterm to (make new terminal)
	tell myterm


	FILE SPACING:

	# double space a file
	sed G

	# double space a file which already has blank lines in it. Output file
	# should contain no more than one blank line between lines of text.
	sed '/^$/d;G'

-Regex
-"(\$)([0-9]*),?([0-9]*),?([0-9]*)(\.?)([0-9]*+ *)"
-Replace
-"$1$2$3$4$5$6"
-Finds "$999,999,999.99 " literal and replaces it with "$999999999.99 "

	1. Create new container
	a) docker run -i -t ubuntu /bin/bash
	b) docker run --name rails_dev_container -i -t ubuntu ubuntu /bin/bash
	The command line flags - i -t provide an interactive shell in the new container

	2. Show running docker containers ==> docker ps

	3. Show list of current containers ==>
	a) docker ps -a (Show all containers, both stopped and running)
	b) docker ps -n x (shows the last x containers, running or stopped, ex: docker ps -n 5)