> (I just wish I understood what in meant in "Effective Programs" by "typos are not important". They are, aren't they ? A typo is a runtime error begging to occur during the demo, how is that "not important" ? Never mind.)

They are going to create an error that you can see and fix immediately, in the vast majority of cases. Certainly in compiled languages (like clojure), but less so in interpreted languages like python, where a misspelled variable in a hidden part of the code may not cause an exception until that part of the code is run.

At least, that's my understanding of what he means by typos being less important than other types of mistakes.

By the way, when I saw his comment originally I was surprised too. But when comparing to the other kind of mistakes he talks about I realized that, yes, I'd rather have a typo than any of the other problems! Though of course, I'd prefer to have none :)