Programs are made up of Dijkstra’s three structures: Sequence, Selection, and Iteration. Each of these is based upon jumps. Sequential statements jump from the end of the first to be beginning of the second.
Selection statements (ifs) jump to the code selected by the predicate and then to the statement after the selection. Loops jump from the end of the loop back to the predicate; and then to the statement after the loop.
Functional programs are not based on jumps. Sequence is determined by function composition: f(g(x)) means that g comes before f. No jump, just function calls.
Selection is based on a predicate that decides which expression to evaluate and return. (If predicate t f) Again, just function calls, no jumps. Iteration is accomplished by recursive function calls. No jumps, just function calls.
Perhaps not profound, but I find it interesting that the three elements of structured programming exist both in imperative and functional languages in such different forms.
