DenkzeitWiki

Main /

Bottom Up Programming

REPL
PaulGraham

Abstractions
LargeScaleApps

It’s worth emphasizing that bottom-up design doesn’t mean just writing the same program in a different order. When you work bottom-up, you usually end up with a different program. Instead of a single, monolithic program, you will get a larger language with more abstract operators, and a smaller program written in it. Instead of a lintel, you’ll get an arch. [1]

• http://www.oreillynet.com/pub/wlg/4857

Although some object-oriented software is reusable, what makes it reusable is its bottom-upness, not its object-orientedness. PaulGraham

• Holon:BottomUp
• Bottom-up programming
  
• Software Is a Many-Layered Thing
  
• Top-down and bottom-up design

---

The following is taken (copied actually) from a write-up of one of PaulGraham's essays Bottom-Up Programming:

1. the higher you build up the language, the less distance you will have to travel from the top down to it
2. changing the language to suit the problem
3. build the language up toward your program
4. As you're writing a program you may think "I wish [I] had such-and-such an operator." So you go and write it.
5. Language and program evolve together.
6. In the end your program will look as if the language had been designed for it. And when language and program fit one another well, you end up with code which is clear, small, and efficient.

"I cannot imagine how the dynamic folks can maintain medium to large projects without refactoring over several iterations over several years of requirement additions and changes."

Perhaps they compose larger software from smaller independent parts, rather than composing large software from large interdependent parts.[2]