Doin’ the blog roundup today, two items really had me shaking my head in amazement.

First was the news (via LtU and lemonodor) that Yahoo! has finally succeeded in moving Yahoo! Stores (originally Viaweb) from its Common Lisp roots to a new, C++ implementation. But only sort of—in Paul Graham’s message about the switch, he reveals that the new implementation contains a new Lisp interpreter. (This is no surprise, really, since the store interface requires a runtime Lisp interpreter.)

In combination with that, what’s really puzzling is this comment: “The reason they rewrote it was entirely that the current engineers didn’t understand Lisp and were too afraid to learn it.”

Just after reading about Yahoo! Stores, I read Bill Venners’ account of some excellent and well known programmers discussing programmer interview tactics. There’s a lot of good stuff in there, including this from Dave Thomas:

Hire for talent. […] The world changes, so you need to hire folks who change with it. Look for people who know computing, not necessarily particular narrow niches. Not only will they adapt better in the future, they’re also more likely to be innovative in the present.

and from Chris Sells:

To identify how good the candidates are technically, I let them choose an area in which they feel they have expertise. I need them to know something well, and I ask them about that. […] I’m not necessarily after an expert in the area I need. If they learned why in the past, I have confidence they’ll learn why in the future.

Now let’s return to the original story about Yahoo! Stores. On LtU, Ehud Lamm quite reasonably wonders “whether maintaining a Lisp interpreter written in C++ is cheaper than sending new engineers to study Lisp.”

I’d like to emphasize the phrase “new engineers” in that sentence. If you have engineers who are afraid to go learn Lisp in order to maintain an extremely successful existing application written in Lisp (but who paradoxically think it’s fine to write their own Lisp implementation to support the customer base) then you need new engineers.