Chris Corbyn d11wtq

Comparing the power and expressiveness of various database query systems

Simple select all.

SELECT * FROM users;

User.all

	%% @doc A binary tree implementation in Erlang.
	%% A binary tree stores keys and values.

	-module(binary_tree).
	-export([init/0, init/1, insert/3, lookup/2]).
	-define(EMPTY_NODE, {node, 'empty'}).

	%% @doc Initialize an empty binary tree node.
	%% This is how the root of the tree should be established.
	%%

	%% @doc Reverse Polish Notation Calculator.
	%%
	%% Parses expressions like "1 2 3 + -" = -4
	%%
	%% This is an exercise in Learn You some Erlang for Great Good,
	%% however I didn't read the text and just implemented it.
	%%
	%% I guess understanding stack-based parsing helps here.
	-module(calc).
	-export([rpn/1]).

	%% @doc This implements a kitchen fridge that you can put things into
	%% and take them out.
	%%
	%% It is stateful, through the use of recursion.
	%% I opted for the sets module only because I wanted to try it.
	%% Using the sets module has the side-effect that you can only store
	%% one of each food item in the fridge.
	-module(kitchen).
	-export([new/0, store/2, take/2]).

	# foldl() is fundamental. With a fold, you can do everything else.
	def foldl(list, acc, &fn)
	if list == [] # base case, return the accumulator
	acc
	else
	head, *tail = list
	foldl(tail, fn.call(acc, head), &fn) #recurse on the remainder
	end
	end

	(defun colorize-mode-line (&rest args)
	(let ((color (cond ((evil-insert-state-p) "#fa4444")
	((evil-emacs-state-p) "#fafa00")
	((buffer-modified-p) "#22bff0"))))
	(set-face-background 'mode-line (or color "#ffffff"))))

	(add-to-list 'post-command-hook 'colorize-mode-line)

	;; vim-style increment/decrement numbers
	(defun inc-number-at-point (n)
	"Increment the number under the point, if present.
	Called with a prefix argument, changes the number by N."
	(interactive "p")
	(let ((amt (or n 1))
	(word (thing-at-point 'word))
	(bounds (bounds-of-thing-at-point 'word)))
	(when (string-match "^[0-9]+$" word)
	(replace-string word

	(defmacro demo-> [val & fns]
	(reduce (fn [acc fname] (list fname acc)) val fns))

	(macroexpand '(demo-> 42 inc dec inc)) ; (inc (dec (inc 42)))

	(defschedule app-schedule "Application tasks"
	[:every "5 seconds" (println "Woohoo!")]
	[:at "7am tomorrow" (wake-up!)])