東 lldong

Category theory jargon cheat sheet

A primer/refresher on the category theory concepts that most commonly crop up in conversations about Scala or FP. (Because it's embarassing when I forget this stuff!)

I'll be assuming Scalaz imports in code samples, and some of the code may be pseudo-Scala.

Functor

A functor is something that supports map.

	// Compile with clang -framework Foundation sethack.m

	#import <Foundation/Foundation.h>
	#import <objc/runtime.h>

	/*
	CFHashBytes from http://www.opensource.apple.com/source/CF/CF-1153.18/CFUtilities.c
	*/
	#define ELF_STEP(B) T1 = (H << 4) + B; T2 = T1 & 0xF0000000; if (T2) T1 ^= (T2 >> 24); T1 &= (~T2); H = T1;

	You can specify the underlying name for a C function the linker/compiler should actually use. If you use an existing
	function's name, it will just let you refer to it with your prototype's name. If you define the function, it'll give
	it that name. It even complains if a function of that name already exists. Tested with clang on a Mac, but AFAIK also
	works in GCC. You can even use special characters in your function names, like you can do in assembly.

	{-# LANGUAGE OverloadedStrings #-}
	module DGPHParser(parseDgph) where

	import qualified Data.Attoparsec.ByteString as A
	import qualified Data.ByteString as B
	import Data.Bits
	import Data.Foldable (foldl')
	import qualified Data.ByteString as B
	import qualified Data.Attoparsec.ByteString as A

 public struct Error: ErrorType {
     let source: String; let reason: String
     public init(_ source: String = __FILE__, _ reason: String) {
         self.reason = reason; self.source = source
     }
 }
 protocol Contextualizable {}
 extension Contextualizable {
     func functionContext(function : String = __FUNCTION__) -> String {

	#!/usr/bin/env bash

	# If your OS X WiFi connection stops working, but can be fixed by
	# toggling WiFi off and then on, this script can help prevent mouse arm.
	# Pings Apple's server repeatedly, toggling WiFi off/on when a connection times out.
	while true ; do
	curl --head --silent --connect-timeout 10 http://www.apple.com/my-wifi-keeps-dropping-out > /dev/null
	if [ $? -ne 0 ] ; then
	networksetup -setairportpower en1 off
	networksetup -setairportpower en1 on

	/*
	* This is an example provided by Facebook are for non-commercial testing and
	* evaluation purposes only.
	*
	* Facebook reserves all rights not expressly granted.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
	* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NON INFRINGEMENT. IN NO EVENT SHALL
	* FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN

	// hpp:

	/// A smart pointer that can manage the lifecycle of Core Foundation objects.
	template<typename T>
	class CFPointer {
	public:
	CFPointer() : storage(nullptr) { }

	CFPointer(T pointer) : storage(toStorageType(pointer)) {
	if (storage) {

	@implementation UIClassSwapper

	- (instancetype) initWithCoder:(UINibDecoder *)decoder
	{
	NSString *className = [decoder decodeObjectForKey:@"UIClassName"];
	NSString *originalClassName = [decoder decodeObjectForKey:@"UIOriginalClassName"];

	Class class = NSClassFromString(className);
	Class originalClass = NSClassFromString(originalClassName);

	// Xcode 6.3 defines new language features to declare nullability
	#if __has_feature(nullability)
	#define PSPDF_ASSUME_NONNULL_BEGIN _Pragma("clang assume_nonnull begin")
	#define PSPDF_ASSUME_NONNULL_END _Pragma("clang assume_nonnull end")
	#define ps_nullable nullable
	#define ps_nonnull nonnull
	#define ps_null_unspecified null_unspecified
	#define ps_null_resettable null_resettable
	#define __ps_nullable __nullable
	#define __ps_nonnull __nonnull