Sorry for the poor quality notes of part 4, but I didn't had the time to fully review this part. I hope that the code examples will be good start to experiment
Examples of lists
[rob, john, lisa, conner].
[josh, jake, eat(cheese)].
[Head|Tail]
Example:
[Head|Tail] = [josh, jake, eat(cheese)].
Only non empty list can have Head and Tail
If you run:
[Head|Tail] = [].
You will get false
Example
[X,Y|W] = [[], ryan, john, eat(cheese)].
[_, _, [_ | X]|_] = [[], dead(z), [2, [b,c]], [], z, [2,[b,c]]]
Will get only:
[[b,c]]
Build-in library called member, and you ask does this member exists in some list or some pair.
Does the X exists in the H or T of the list.
member(X, [H|T]).
member is a function defined in a recursive manner.
This returns true when: X is the Head of the List if not we are going to call some list and
member(X, [X|T]).
member(X, [H|T]) :-
member(X,T).
This is an example of reccursion
If you have list of
[1, 2, 3, 4]
Is 3 a member of the list.
Ok 3 is not the member of the Head H
Then will pass [2, 3, 4] as the list
Then will pass [3, 4] as the list
The 3 will is equal the Head H and will satisfy the stopping condition
member(X, [X|T]).
and it will stop and return true.
Examples:
member(jan, [jan, josh, judy]).
member(troy, [josh, jan, troy]).
Both return true
member(troy, [josh, jan, judy]);
will return false
member(X, [23,25,67,12,25,19,9,6]),
Y is X*X, Y<400
We are going to build a change machine.
-
It is goign to return a change for 1 dollar.
-
It is going to consist of change
- half dolars (50 cents)
- quotors (25 cents)
- dimes (10 cents)
- nikels (5 cents)
- pennys (1 cent)
change(H, Q, D, N, P) :-
member(H, [0 ,1, 2]),
member(Q, [0, 1, 2, 3, 4]),
member(D, [0, 1 ,2, 3, 4, 5, 6, 7, 8, 9, 10]),
member(N, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]),
S is 50*H + 25*Q + 10*D + 5*N,
S =< 100,
P is 100-S.
change(H, 0, 0, 0, 0).
change(0, 0, 0, 0, P).
change(0, 3, 0, 0, P).
no work files