I’m not arguing against type theories, not arguing against the usefulness of various forms of type inference, not arguing against reasonable requests, not arguing against the desire to reason about code, not arguing against tools to ensure correctness and all that good stuff.

I am arguing against the belief that types belong in the compiler and not in the running system, and I am arguing that the specific idea of a “parameterized type” is moot in Common Lisp, both because we have typed objects and because we have a type hierarchy for all types with specialization on disjoint types.

I am arguing that parameterized types are necessary when you accept disjoint types and believe in the compiler as your only savior.

Steve Yegge is always awesome.

I recently came across this excerpt:

Desperate or not, those people aren’t going to work for me. I demand excellence from my co-workers. The disease, nay, the virus of programming-language religion has a simple cure: you just write a compiler. Or an interpreter. One for any language other than the one you know best. It’s as easy as that. After you write a compiler (which, to be sure, is a nontrivial task, but if there’s some valid program out there that you couldn’t ever write, then you’re not justified in calling yourself a programmer), the disease simply vanishes. In fact, for weeks afterwards, you can’t look at your code without seeing right through it, with exactly the same sensation you get when you stare long enough at a random-dot stereogram: you see your code unfold into a beautiful parse tree, with scopes winding like vines through its branches, the leaves flowering into assembly language or bytecode.

When you write a compiler, you lose your innocence. It’s fun to be a shaman, knowing that typing the right conjuration will invoke the gods of the machine and produce what you hope is the right computation. Writing a compiler slays the deities, after which you can no longer work true magic. But what you lose in excitement, you gain in power: power over languages and over language-related tools. You’ll be able to master new languages rapidly and fearlessly. You may lose your blind faith, but you gain insight into the hauntingly beautiful machinery of your programs. For many, it deepens their real faith. Regardless, it lets them sit at the table with their peers as equals.

From here

… a trivial (in retrospect) method for entirely relieving compilers of the burden of stack discipline: a necessary first step towards relieving programmers of the burden of compilers. A systems programmer or electrical engineer educated in the present Dark Age might ask why we ought to demand relief from CPUs which force machine code to “drive stick” in register allocation and stack discipline. After all, have we not correctly entrusted these tasks to optimizing compilers? Should we not continue even further in this direction?