Matematics vs Computer science

For several years I'm working with mathematicians. And I think this citation very clear expresses the cause of difficulties in communication:

"In mathematics we are usually concerned with declarative (what is) description, whereas in computer science we are usually concerned with imperative (how to) descriptions"

From Hal Abelson's, Jerry Sussman's and Julie Sussman's Structure and Interpretation of Computer Programs

SICP about Lisp

Lisp obeys the convention that every expression has a value. This convention, together with the old reputation of Lisp as an inefficient language, is the source of quip by Alan Perlis (paraphrasing Oscar Wilde) that "Lisp programmers knows the value of everything but the cost of nothing".

From Hal Abelson's, Jerry Sussman's and Julie Sussman's Structure and Interpretation of Computer Programs