Know Your History
Brit Butler
2014/11/12
Disclaimer
This talk will be a little different...
3 Core Points and an overarching theme...
Know Your Damn History
- Whence the Web?
- We're Programmer Archaeologists
- There Is No Magic
Whence the Web?
Whence the Web?
Let's go back to September '95...
Search engines aren't a thing.
Geocities and AOL still exist.
SSL was invented that February.
No browsers support CSS (1.0) yet.
Web pages can't do anything interesting yet.
Whence the Web?
Netscape asks Brendan Eich to write Javascript. Why?
Make webpages suck less by adding dynamic behavior.
Current alternative was Java applets. Blech.
Brendan writes the language and its called 'Livescript'.
Marketing christens it 'Javascript' later. Demands syntax changes.
Whence the Web?
What might Brendan have said about JS in 2008?
Whence the Web?
As you may know, I wrote javascript in ten days.
...
The part that is good is not original, and the part that is original is not good.
- 2008, Brendan Eich, Popularity
Engine prototype took ten days in May.
...
The rest of the year was browser integration, mainly what became known as “DOM level 0″...
Sentence fragments here show my PTSD from that sprint. :-/
- 2011, Brendan Eich, New JS Engine Module Owner
Whence the Web?
What can we take away from that?
Whence the Web?
Even Javascript is just another program.
This sounds trite but has profound implications.
Which we'll get into in the third section of this talk.
Whence the Web?
The Best Tech Doesn't Matter
- Social forces dominate technology choice.
- What you build with your tools matters much more than the tools themselves.
- There is a lot of cool tech that is forgotten or died out.
- Even if you can't use it, you can learn from it.
See: The Lively Kernel, Logic Programming, etc
Whence the Web?
Requirements Will Change
'Can you make it look more like Java?'
How do we control the damage?
- Before: Encapsulation, Single Responsibility Principle, Etc.
- Don't grow the sprint, change the sprint.
- Try to limit scope as much as possible.
Whence the Web?
Technical Debt is very real.
We all live with it.
- Stuff gets pushed out the door for business reasons.
You're stuck with that until people stop using it. - jQuery 1.0 was released in 2006. Gmail was out in 2004.
- Promises are just now being added to javascript.
- Modules still aren't a solved problem.
See: browserify, requirejs, google closure, es6 modules
We're Programmer Archaeologists
So let's talk about Technical Debt.
We're Programmer Archaeologists
Wait until you can look at code you wrote 6 months ago.
We're Programmer Archaeologists
You will be working on old code more often than writing new code.
This is both blessing and curse.
Some days bugfixing is really nice.
But often, we have to understand the assumptions embedded in code.
We're Programmer Archaeologists
Why do changes to one piece of code break things elsewhere?
We're Programmer Archaeologists
Every program is part of some other program and rarely fits.
-- Alan Perlis, Epigrams on Programming
We're Programmer Archaeologists
Programs Don't Compose. Even if James says otherwise.
Certainly functions can compose, especially pure ones.
But modules and programs don't, generally speaking.
We can't put photoshop and an audio editor together and get a video editor.
We're Programmer Archaeologists
Building larger programs out of a group of small, understandable pieces is what things like recursion and functional programming are built for.
The world isn't like that anymore.
We're Programmer Archaeologists
This makes me kind of sad.
Old curriculum was for a world that built things from scratch.
New curriculum is for a world that's all about reuse.
We've really never slowed down since the dot com boom.
But there is good news...
There Is No Magic
You can understand how computers work!
- Vast majority of computer behavior is deterministic, repeatable.
- They follow simple (okay, elaborate) sets of rules.
- The basics of programming have been the same for 30-40 years.
- You can almost always drill down even though there's lots of code.
- At a high level, CPUs and PLs work in a straightforward way.
There Is No Magic
How CPUs Work
- Read a variable (technically a 'register') called the program counter.
- Program Counter holds the location of the code to run next.
- Run that code. That code updates the program counter.
- Start over from the top. Do this forever.
There Is No Magic
PS: I Love emulation.
See also: JSNES
There Is No Magic
How PLs Work
- Compiled: Translate language X into language Y that something else can run.
- Interpreted: Read Language X line by line and execute it directly.
Okay, technically a little more complicated. (read: lots)
Most JS implementations are JIT-compiled which is a sort of hybrid technique.
There Is No Magic
Can talk about this a lot more if folks are interested.
cl-6502 can be thought of as an interpreter for assembly language.
Very dumb/naive though. No AST. No rewriting.
There Is No Magic
A Magic Trick For Your Entertainment
How do you create arrays in a language with nothing but lexical scoping and first-class functions?
- Stolen from SICP, Chapter 2, Problem 4
Spoilers