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Functional Java is an open source library that supports closures for the Java programming language
package fj;
/**
* Represents the bottom _|_ value.
*
* @version %build.number%
*/
public final class Bottom {
private Bottom() {
throw new UnsupportedOperationException();
}
/**
* Returns an error to represent undefinedness in a computation.
*
* @return An error to represent undefinedness in a computation.
*/
public static Error undefined() {
return error("undefined");
}
/**
* Returns an error to represent undefinedness in a computation with early failure using the given
* message.
*
* @param s The message to fail with.
* @return An error to represent undefinedness in a computation with early failure using the given
* message.
*/
public static Error error(final String s) {
throw new Error(s);
}
/**
* Provides a thunk that throws an error using the given message when evaluated.
*
* @param s The message to fail with.
* @return A thunk that throws an error using the given message when evaluated.
*/
public static P1 error_(final String s) {
return new P1() {
@Override public A _1() {
throw new Error(s);
}
};
}
/**
* Provides a function that throws an error using the given message, ignoring its argument.
*
* @param s The message to fail with.
* @return A function that throws an error using the given message, ignoring its argument.
*/
public static F errorF(final String s) {
return a -> {
throw new Error(s);
};
}
/**
* Represents a deconstruction failure that was non-exhaustive.
*
* @param a The value being deconstructed.
* @param sa The rendering for the value being deconstructed.
* @return A deconstruction failure that was non-exhaustive.
*/
public static Error decons(final A a, final Show sa) {
return error("Deconstruction failure on type " + a.getClass() + " with value " + sa.show(a).toString());
}
/**
* Represents a deconstruction failure that was non-exhaustive.
*
* @param c The type being deconstructed.
* @return A deconstruction failure that was non-exhaustive.
*/
@SuppressWarnings({"UnnecessaryFullyQualifiedName"})
public static Error decons(final java.lang.Class c) {
return error("Deconstruction failure on type " + c);
}
/**
* A function that returns the toString for a throwable.
*
* @return A function that returns the toString for a throwable.
*/
public static F eToString() {
return t -> t.toString();
}
/**
* A function that returns the getMessage for a throwable.
*
* @return A function that returns the getMessage for a throwable.
*/
public static F eMessage() {
return t -> t.getMessage();
}
}