SafeHead (hydra-java 0.14.1 API)

java.lang.Object
- hydra.tools.PrimitiveFunction
- - hydra.lib.lists.SafeHead

public class SafeHead
extends PrimitiveFunction

Safely returns the first element.

Constructor Summary

Constructors
Constructor Description

SafeHead()

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static <X> Maybe<X>`	`apply(ConsList<X> list)`	Apply the function to it single argument.
`protected java.util.function.Function<java.util.List<Term>,java.util.function.Function<Context,java.util.function.Function<Graph,Either<InContext<Error_>,Term>>>>`	`implementation()`	A dynamic/interpreted implementation of the function.
`Name`	`name()`	The unique name of the primitive function.
`TypeScheme`	`type()`	The datatype of the primitive function.

Methods inherited from class hydra.tools.PrimitiveFunction
term, toNative

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - SafeHead
```
public SafeHead()
```
- Method Detail
  - name
```
public Name name()
```
    Description copied from class: PrimitiveFunction
    
    The unique name of the primitive function.
    
    Specified by:
    
    name in class PrimitiveFunction
    
    Returns:
    
    the name of this primitive function
  - type
```
public TypeScheme type()
```
    Description copied from class: PrimitiveFunction
    
    The datatype of the primitive function.
    
    Specified by:
    
    type in class PrimitiveFunction
    
    Returns:
    
    the type scheme of this primitive function
  - implementation
```
protected java.util.function.Function<java.util.List<Term>,java.util.function.Function<Context,java.util.function.Function<Graph,Either<InContext<Error_>,Term>>>> implementation()
```
    Description copied from class: PrimitiveFunction
    
    A dynamic/interpreted implementation of the function. Subclasses implement this with Either-based logic.
    
    Specified by:
    
    implementation in class PrimitiveFunction
    
    Returns:
    
    the function implementation
  - apply
```
public static <X> Maybe<X> apply(ConsList<X> list)
```
    Apply the function to it single argument.
    
    Type Parameters:
    
    X - the element type
    
    Parameters:
    
    list - the list to get the head from
    
    Returns:
    
    an optional containing the first element, or empty if the list is empty