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hrldcpr / tree.md
Last active January 24, 2026 21:18
one-line tree in python

One-line Tree in Python

Using Python's built-in defaultdict we can easily define a tree data structure:

def tree(): return defaultdict(tree)

That's it!

@hrldcpr
hrldcpr / whyhaskelliscool.lhs
Created April 20, 2012 16:37
Why Haskell is Cool
Haskell is cool!
Here are some reasons why.
(This is a Literate Haskell file, so you can load it and then follow
along with the examples by running `ghci whyhaskelliscool.lhs`)
"Pattern matching" syntax for defining functions is cool, letting you
avoid 'if' statements and simply write out the different behaviors of
a function:
@hrldcpr
hrldcpr / evernote-crontab
Created December 15, 2012 18:27
crontab to make Evernote for Mac sync every minute. to edit your crontab, open Terminal and run `EDITOR=nano crontab -e`
* * * * * osascript -e 'if application "Evernote" is running then tell application "Evernote" to synchronize'
@hrldcpr
hrldcpr / gist:4429798
Last active December 10, 2015 11:48
example of trying to use svg in meteor
<head>
<title>Leaderboard</title>
</head>
<body>
<div id="outer">
{{> leaderboard}}
</div>
</body>
@hrldcpr
hrldcpr / gist:4645623
Created January 27, 2013 01:02
convection on http://syzygy.st
for (var v = 0; v < 2*N; v++) {
for (var u = -N; u < N; u++) {
var w = getCube(u, v);
if (w > 0 && w < tick) { // there's a cube and it's not one we just created
setCube(u, v, 0); // remove it
if (u < N && v > 0) {
if (Math.random() < 0.5) // 50% of the time
setCube(u + 1, v - 1, tick); // directly above
if (Math.random() < 0.25) // 25% of the time
setCube(u + 1, v - 2, tick); // above-left
@hrldcpr
hrldcpr / iwish.hs
Last active December 12, 2015 12:39
dedup [] = []
dedup (x:xs) = dedup' x xs
where
dedup' x [] = [x]
dedup' x (x:xs) = dedup' x xs
dedup' y (x:xs) = y : dedup' x xs
@hrldcpr
hrldcpr / lazygreedy.md
Last active August 29, 2015 14:04
comparison of lazy and greedy regex performance

greedy - <img [^>]*>

python3 -m timeit -s 'import re; r = re.compile(r"<img [^>]*>")' \
'r.findall("<img src alt name etc> <img even more stuff forever dot com forward slash junk.html and stuff>")'

1000000 loops, best of 3: 0.72 usec per loop

lazy - ``

@hrldcpr
hrldcpr / Reading.hs
Created July 28, 2014 16:23
simple example of Reader monad
import qualified Data.Maybe as Maybe
import qualified Control.Monad.Reader as Reader
type Environment = [(String, String)]
get :: String -> Environment -> String
get k env = Maybe.fromJust $ lookup k env
@hrldcpr
hrldcpr / install_docker.md
Last active August 29, 2015 14:04
installing Docker on a Mac, such that `docker run -v ...` works for anything under /Users

First, install VirtualBox. Then:

brew update
brew upgrade
brew install docker boot2docker

mkdir ~/.boot2docker
curl http://static.dockerfiles.io/boot2docker-v1.1.2-virtualbox-guest-additions-v4.3.12.iso \
> ~/.boot2docker/boot2docker.iso
@hrldcpr
hrldcpr / liftM.hs
Created July 31, 2014 14:50
three different implementations of liftM
liftM f m = m >>= (return . f)
liftM f m = do
a <- m
return (f a)
-- which is just sugar for:
liftM f m =
m >>= \a ->