What is a subroutine?

Define Function with respect to Programming language.

Write the inference you get from X : = (78).

Differentiate interface and implementation.

Which of the following is a normal function definition and which is recursive function definition
i) let rec sum x y:
   return x + y
ii) let disp:
    print ‘welcome’
iii) let rec sum num:
     if (num!=0) then return num + sum (num-1)
     else
     return num