The hardest single part of building a software system is deciding precisely what to build.

λ演算本质上是一个关于函数及其应用的理论。

If you ask an economist what’s driven economic growth, it’s been major advances in things that mattered – the mechanization of farming, mass manufacturing, things like that. The problem is, our society is not organized around doing that.

The way we see things is affected by what we know or what we believe.