CLP(R) is a
declarative programming language
In computer science, declarative programming is a programming paradigm—a style of building the structure and elements of computer programs—that expresses the logic of a computation without describing its control flow.
Many languages that ap ...
. It stands for
constraint logic programming
Constraint logic programming is a form of constraint programming, in which logic programming is extended to include concepts from constraint satisfaction. A constraint logic program is a logic program that contains constraints in the body of clau ...
(Real) where real refers to the
real number
In mathematics, a real number is a number that can be used to measure a ''continuous'' one-dimensional quantity such as a distance, duration or temperature. Here, ''continuous'' means that values can have arbitrarily small variations. Every real ...
s. It can be considered and is generally implemented as a superset or add-on package for a
Prolog
Prolog is a logic programming language associated with artificial intelligence and computational linguistics.
Prolog has its roots in first-order logic, a formal logic, and unlike many other programming languages, Prolog is intended primarily ...
implementation.
Example rule
The
simultaneous linear equations
In mathematics, a system of linear equations (or linear system) is a collection of one or more linear equations involving the same variables.
For example,
:\begin
3x+2y-z=1\\
2x-2y+4z=-2\\
-x+\fracy-z=0
\end
is a system of three equations in th ...
:
:
are expressed in CLP(R) as:
3*X + 4*Y - 2*Z = 8,
X - 5*Y + Z = 10,
2*X + 3*Y -Z = 20.
and a typical implementation's response would be:
Z = 35.75
Y = 8.25
X = 15.5
Yes
Example program
CLP(R) allows the definition of predicates using recursive definitions. For example a mortgage relation can be defined as
relating the principal P, the number of time periods of the loan T, the repayment each period R, the interest rate per period I
and the final balance owing at the end of the loan B.
mg(P, T, R, I, B) :- T = 0, B = R.
mg(P, T, R, I, B) :- T >= 1, P1 = P*(1+I) - R, mg(P1, T - 1, R, I, B).
The first rule expresses that for a 0 period loan the balance owing at the end is simply the original principal.
The second rule expresses that for a loan of at least one time period we can calculate the new owing amount P1 by
multiplying the principal by 1 plus the interest rate and subtracting the repayment. The remainder of the loan
is treated as another mortgage for the new principal and one less time period.
What can you do with it? You can ask many questions.
If I borrow 1000$ for 10 years at 10% per year repaying 150 per year, how much will I owe at the end?
?- mg(1000, 10, 150, 10/100, B).
The system responds with the answer
B = 203.129.
How much can I borrow with a 10 year loan at 10% repaying 150 each year to owe nothing at the end?
?- mg(P, 10, 150, 10/100, 0).
The system responds with the answer
P = 921.685.
What is the relationship between the principal, repayment and balance on a 10 year loan at 10% interest?
?- mg(P, 10, R, 10/100, B).
The system responds with the answer
P = 0.3855*B + 6.1446 * R.
This shows the relationship between the variables, without requiring any to take a particular value.
References
* Joxan Jaffar, Spiro Michaylov, Peter J. Stuckey, Roland H. C. Yap
The CLP(R) Language and System ACM Transactions on Programming Languages and Systems 14(3): 339-395 (1992)
External links
How To CLP(R)CLP(R) Programming Manual
Declarative programming languages
Constraint programming
Logic programming
Constraint logic programming
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