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Library for use in Java components of Vespa. Shared code which do not fit anywhere else.

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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.tensor.functions;

import com.yahoo.tensor.evaluation.EvaluationContext;
import com.yahoo.tensor.evaluation.Name;

import java.util.Optional;
import java.util.function.Function;

/**
 * A function which returns a scalar
 *
 * @author bratseth
 */
public interface ScalarFunction extends Function, Double> {

    @Override
    Double apply(EvaluationContext context);

    /** Returns this as a tensor function, or empty if it cannot be represented as a tensor function */
    default Optional> asTensorFunction() { return Optional.empty(); }

    default String toString(ToStringContext context) { return toString(); }

}