Predicate (Sleep 2.1 API)

All Known Implementing Classes:

BasicNumbers, BasicStrings, BasicUtilities
```
public interface Predicate
```
A predicate is an operator used inside of comparisons. Comparisons are used in if statements and loop constructs. Sleep supports two types of predicates. A unary predicate which takes one argument. The other type is a binary (normal) predicate which takes two arguments. In the example comparison a == b, a is the left hand side, b is the right hand side, and == is the predicate. Predicate bridges are used to add new predicates to the language.

To install a predicate into a script environment:
```
 ScriptInstance script;           // assume
 Predicate      myPredicateBridge; // assume
 
 Hashtable environment = script.getScriptEnvironment().getEnvironment();
 environment.put("isPredicate", myPredicateBridge);
 
```
In the above code snippet the script environment is extracted from the script instance class. A binary predicate can have any name. A unary predicate always begins with the - minus symbol. "isin" would be considered a binary predicate where as "-isletter" would be considered a unary predicate.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`decide(java.lang.String predicateName, ScriptInstance anInstance, java.util.Stack passedInTerms)`	decides the truthfulness of the proposition predicateName applied to the passedInTerms.

- Method Detail
  - decide
```
boolean decide(java.lang.String predicateName,
               ScriptInstance anInstance,
               java.util.Stack passedInTerms)
```
    decides the truthfulness of the proposition predicateName applied to the passedInTerms.
    
    Parameters:
    
    predicateName - a predicate i.e. ==
    
    anInstance - an instance of the script asking about this predicate.
    
    passedInTerms - a stack of terms i.e. [3, 4]. These arguments are passed in REVERSE ORDER i.e. [right hand side, left hand side]
    
    Returns:
    
    a boolean, in the case of a predicate == and the terms [3, 4] we know 3 == 4 is false so return false.