Bratko, Chapter3: Lists, Operators and Arithmetic

- lists
  - e.g., [] empty list
          [a,b,c]
          [bob,tom,jim]
  - elements of lists are any valid Prolog data object
  - lists built using the .(Head,Tail) functor (i.e., cons in Lisp)
    - e.g., [a,b,c] = .(a,.(b,.(c,[])))
  - vetical bar | notation
    - e.g., [a,b,c] = [a|[b,c]] = [a|[b|[c]]] = [a|[b|[c|[]]]]
                      [a,b|[c]] = [a,b,c|[]]
  - operations on lists
    - e.g., member(X,L) :- L = [X|_].
            member(X,L) :- L = [A|B], member(X,B).
         OR
            member(X,[X|_]).
            member(X,[_|B]) :- member(X,B).
    - append(L1,L2), cons(X,L), remove(X,L), sublist(L1,L2), permute(L1,P)
- operators
  - used for shorthand (more readable) notation
  - e.g., +, -, *, /, |, ., :-, ...
  - bob likes pam ---> likes(bob,pam)
  - pam likes tom and tom likes pam --> and(likes(pam,tom),likes(tom,pam))
  - :- op(Precedence,Type,Name).
    - Precedence in [1,1200] [see Fig 3.8 for typical ops]
      - higher precedence ops appear further out in expression
      - lower precedence bind first
    - Type is one of: xfx, xfy, yfx, fx, fy, xf, yf
      - x: argument precedence less than operator precedence
      - y: argument precedence less than or equal to operator precedence
    - Name is an atom
  - e.g., :- op(600,xfy,and).
          :- op(500,xfx,likes).
    - (a and b and c) --> and(a,and(b,c)) not and(and(a,b),c)
    - a likes b and c likes d --> and(likes(a,b),likes(b,c))
- arithmetic
  - +, -, *, /, mod
  - assignment 'is' not '=' (unification)
  - >, <, >=, =<, =:= (equal), =\= (not equal)
  - examples: gcd, length

Examples
- factorial
- member
- square root
- nth [HW1]
- monkey and banana [fig2.14]
  - augment to get solution [HW1]