Why exactly is eval evil?

Question

I know that Lisp and Scheme programmers usually say that eval should be avoided unless strictly necessary. I’ve seen the same recommendation for several program

Answer 1

Like the GOTO "rule": If you don't know what you are doing, you can make a mess.

Besides from only building something out of known and safe data, there's the problem that some languages/implementations can't optimize the code enough. You could end up with interpreted code inside eval.