If you, like me, resent every dollar spent on commercial PDF tools,
you might want to know how to change the text content of a PDF without
having to pay for Adobe Acrobat or another PDF tool. I didn't see an
obvious open-source tool that lets you dig into PDF internals, but I
did discover a few useful facts about how PDFs are structured that
I think may prove useful to others (or myself) in the future. They
are recorded here. They are surely not universally applicable --
the PDF standard is truly Byzantine -- but they worked for my case.
// I'm tired of extensions that automatically: | |
// - show welcome pages / walkthroughs | |
// - show release notes | |
// - send telemetry | |
// - recommend things | |
// | |
// This disables all of that stuff. | |
// If you have more config, leave a comment so I can add it!! | |
{ |
#include <stdio.h> | |
#define SQ(x) (x)*(x) | |
#define M0(x,y) SQ(x)+SQ(y)<4?0:0xe0 | |
#define M1(x,y,x0,y0) (SQ(x)+SQ(y)<4)?M0(SQ(x)-SQ(y)+(x0),2*(x)*(y)+(y0)):0xc0 | |
#define M2(x,y,x0,y0) (SQ(x)+SQ(y)<4)?M1(SQ(x)-SQ(y)+(x0),2*(x)*(y)+(y0),x0,y0):0xa0 | |
#define M3(x,y,x0,y0) (SQ(x)+SQ(y)<4)?M2(SQ(x)-SQ(y)+(x0),2*(x)*(y)+(y0),x0,y0):0x80 | |
#define M4(x,y,x0,y0) (SQ(x)+SQ(y)<4)?M3(SQ(x)-SQ(y)+(x0),2*(x)*(y)+(y0),x0,y0):0x60 | |
#define M5(x,y,x0,y0) (SQ(x)+SQ(y)<4)?M4(SQ(x)-SQ(y)+(x0),2*(x)*(y)+(y0),x0,y0):0x40 |
UPDATE 2021: I wrote this long before I wrote my book Functional Programming Made Easier: A Step-by-step Guide. For a much more in depth discussion on Monads see Chapter 18.
Initially, Monads are the biggest, scariest thing about Functional Programming and especially Haskell. I've used monads for quite some time now, but I didn't have a very good model for what they really are. I read Philip Wadler's paper Monads for functional programming and I still didnt quite see the pattern.
It wasn't until I read the blog post You Could Have Invented Monads! (And Maybe You Already Have.) that I started to see things more clearly.
This is a distillation of those works and most likely an oversimplification in an attempt to make things easier to understand. Nuance can come later. What we need when first le
/*<?php | |
//*/public class PhpJava { public static void main(String[] args) { System.out.printf("/*%s", | |
//\u000A\u002F\u002A | |
class PhpJava { | |
static function main() { | |
echo(//\u000A\u002A\u002F | |
"Hello World!"); | |
}} | |
//\u000A\u002F\u002A | |
PhpJava::main(); |