frege.runtime

Class Undefined

java.lang.Object

java.lang.Throwable

java.lang.Exception

java.lang.RuntimeException

java.lang.IllegalArgumentException

frege.runtime.Undefined

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

GuardFailed, NoMatch

public class Undefined
extends java.lang.IllegalArgumentException

Exception thrown when the undefined value is evaluated.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
(package private) static long	serialVersionUID
private int	two

Constructor Summary

Constructors

Constructor and Description
Undefined(java.lang.String err) Construct an undefined value from a string, e.g.
Undefined(java.lang.String err, java.lang.Throwable cause) Construct an undefined value from a string and another exception.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	die() Method used by Frege code to throw exceptions.

Methods inherited from class java.lang.Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

two

private int two

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

Constructor Detail

Undefined

public Undefined(java.lang.String err)

Construct an undefined value from a string, e.g.

 
 Prelude.error "you blew it"
 
 

Parameters:

err - description of the error

Undefined

public Undefined(java.lang.String err,
         java.lang.Throwable cause)

Construct an undefined value from a string and another exception.

This is used by Frege code to throw any exception catched from invocation of native functions.
This mechanism avoids throws clauses on frege functions.

Parameters:

err -

cause -

Method Detail

die

public final boolean die()

Method used by Frege code to throw exceptions.

An exception from some native method, wrapped in Undefined can be thrown everywhere without throws clauses or try ... catch ... blocks.

This function actually never returns, but we need some return type to make the Frege type checker happy and also to give the code generator a reason to actually invoke this method.