An Introduction to Functional Programming Through Lambda Calculus

- 238 -starts ((h1::t1):string list) ((h2::t2):string list) =if h1=h2then starts t1 t2else false;fun find1 [] (s2:string list) = 1 |find1 (s1:string list) [] = 1 |find1 (s1:string list) (s2:string list) =if starts s1 s2then 1else 1+(find1 s1 (tl s2));fun find (s1:string) (s2:string) =let val pos = find1 (explode s1) (explode s2)inif pos > (size s2)then 0else posend;5)fun east Queens_Street = Bishopbriggs |east Bishopbriggs = Lenzie |east Lenzie = Croy |east Croy = Polmont |east Polmont = Falkirk_High |east Falkirk_High = Linlithgow |east Linlithgow = Haymarket |east Haymarket = Waverly |east Waverly = Waverly;fun west Queens_Street = Queens_Street |west Bishopbriggs = Queens_Street |west Lenzie = Bishopbriggs |west Croy = Lenzie |west Polmont = Croy |west Falkirk_High = Polmont |west Linlithgow = Falkirk_High |west Haymarket = Linlithgow |west Waverly = Haymarket;6)fun eval (numb(i:int)) = i |eval (add(e1:exp,e2:exp)) = (eval e1)+(eval e2) |eval (diff(e1:exp,e2:exp)) = (eval e1)-(eval e2) |eval (mult(e1:exp,e2:exp)) = (eval e1)*(eval e2) |eval (quot(e1:exp,e2:exp)) = (eval e1) div (eval e2);Chapter 101)i) (defun nsum (n)(if (eq 0 n)