If you want a good 'regular' (numeric) calculator, Prolog would make little to no sense. Likewise, I would not advise you to waste your time on it. Note − The nl is used to create new line. I don't think you can find any good tutorial on this combination of topics, because I fail to imagine a reasonable knowledgeable person who would take this pointless task. for example if we ask: expr(3+x,2,x,S)the answer will be S5 and if we ask expr(5. suppose we have a predicate like this: expr(E,Val,Var,Sol) the first is the expression the second is the value the third one is the variable and the forth one is the result.
#VISUAL PROLOG EXPRESSION IS USED WHEN A FORMULA IS EXPECTED CODE#
Let us see one practical code to understand the usage of these operators. There are few different types of arithmetic operators as follows − Operator Arithmetic Operators in PrologĪrithmetic operators are used to perform arithmetic operations. In the case of 1+A=B+2, A and B are two variables, and they are automatically assigned to some values that will match the pattern. As they are not same, it returns no (false). This is because, in the first case it is checking whether the value of 1 + 2 is same as 2 + 1 or not, and the other one is checking whether two patterns ‘1+2’ and ‘2+1’ are same or not.
Here we can see 1+2=:=2+1 is returning true, but 1+2=2+1 is returning false. Following are different comparison operators − Operator Comparison OperatorsĬomparison operators are used to compare two equations or states. Also we will see some practical demonstration to understand the usage of different operators. We will also see how these are different from any other high level language operators, how they are syntactically different, and how they are different in their work. Types of the comparison operators and Arithmetic operators.
For such a developer, the regular detailed language reference could serve the best.In the following sections, we will see what are the different types of operators in Prolog. In this case, creation of the calculator could be justified, marginally, but in this case I would not advise to look for a tutorial. In addition to having extra hassles, you would risk to go around essence of the logical programming and the essential features of the language.Īnd finally, I can assume that you are already knowledgeable in Prolog and want to polish your skills to make yourself a universal Prolog developer capable of solving nearly any problem. Such task would defeat the purpose of this language. Please see:įrom the other hand, if I assume that you want to make a calculator to learn Prolog, I would advise to find a better goal. Such calculators are possible just because the imperative interpretive languages can parse/evaluate strings containing expressions in the same language, like JavaScript Eval. For example, take a look at my JavaScript calculator: Who need them? Anyone can easily make a decent expression-oriented calculator with any non-trivial scripting/interpretive language, because they have expression evaluators, which just few lines of code. Generally, making a traditionally-looking calculator with buttons is a popular but very poor model for learning programming. Please see:Įven if you use Prolog implementation with enforced (I would say, "artificially enforced") imperative feature, notably Object-Oriented Visual Prolog, formerly Borland Turbo Prolog, it would not match with several much more suitable languages. This is a logic programming language, strongly declarative, with notoriously weak imperative semantics. If you want a good "regular" (numeric) calculator, Prolog would make little to no sense. I don't think you can find any good tutorial on this combination of topics, because I fail to imagine a reasonable knowledgeable person who would take this pointless task.
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