Java tutorial
/* * Copyright (c) 2016 Gridtec. All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package at.gridtec.lambda4j.function.bi.conversion; import at.gridtec.lambda4j.Lambda; import at.gridtec.lambda4j.consumer.bi.BiShortConsumer; import at.gridtec.lambda4j.function.bi.BiFunction2; import at.gridtec.lambda4j.function.bi.BiShortFunction; import at.gridtec.lambda4j.function.bi.to.ToDoubleBiFunction2; import at.gridtec.lambda4j.function.conversion.BooleanToShortFunction; import at.gridtec.lambda4j.function.conversion.ByteToShortFunction; import at.gridtec.lambda4j.function.conversion.CharToShortFunction; import at.gridtec.lambda4j.function.conversion.DoubleToByteFunction; import at.gridtec.lambda4j.function.conversion.DoubleToCharFunction; import at.gridtec.lambda4j.function.conversion.DoubleToFloatFunction; import at.gridtec.lambda4j.function.conversion.DoubleToShortFunction; import at.gridtec.lambda4j.function.conversion.FloatToShortFunction; import at.gridtec.lambda4j.function.conversion.IntToShortFunction; import at.gridtec.lambda4j.function.conversion.LongToShortFunction; import at.gridtec.lambda4j.function.conversion.ShortToDoubleFunction; import at.gridtec.lambda4j.function.to.ToShortFunction; import at.gridtec.lambda4j.operator.binary.DoubleBinaryOperator2; import at.gridtec.lambda4j.operator.binary.ShortBinaryOperator; import at.gridtec.lambda4j.operator.unary.ShortUnaryOperator; import at.gridtec.lambda4j.predicate.bi.BiShortPredicate; import org.apache.commons.lang3.tuple.Pair; import javax.annotation.Nonnegative; import javax.annotation.Nonnull; import javax.annotation.Nullable; import java.util.Map; import java.util.Objects; import java.util.concurrent.ConcurrentHashMap; import java.util.function.DoubleConsumer; import java.util.function.DoubleFunction; import java.util.function.DoublePredicate; import java.util.function.DoubleToIntFunction; import java.util.function.DoubleToLongFunction; import java.util.function.DoubleUnaryOperator; /** * Represents an operation that accepts two {@code short}-valued input arguments and produces a * {@code double}-valued result. * This is a primitive specialization of {@link BiFunction2}. * <p> * This is a {@link FunctionalInterface} whose functional method is {@link #applyAsDouble(short, short)}. * * @see BiFunction2 */ @SuppressWarnings("unused") @FunctionalInterface public interface BiShortToDoubleFunction extends Lambda { /** * Constructs a {@link BiShortToDoubleFunction} based on a lambda expression or a method reference. Thereby the * given lambda expression or method reference is returned on an as-is basis to implicitly transform it to the * desired type. With this method, it is possible to ensure that correct type is used from lambda expression or * method reference. * * @param expression A lambda expression or (typically) a method reference, e.g. {@code this::method} * @return A {@code BiShortToDoubleFunction} from given lambda expression or method reference. * @implNote This implementation allows the given argument to be {@code null}, but only if {@code null} given, * {@code null} will be returned. * @see <a href="https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html#syntax">Lambda * Expression</a> * @see <a href="https://docs.oracle.com/javase/tutorial/java/javaOO/methodreferences.html">Method Reference</a> */ static BiShortToDoubleFunction of(@Nullable final BiShortToDoubleFunction expression) { return expression; } /** * Calls the given {@link BiShortToDoubleFunction} with the given arguments and returns its result. * * @param function The function to be called * @param value1 The first argument to the function * @param value2 The second argument to the function * @return The result from the given {@code BiShortToDoubleFunction}. * @throws NullPointerException If given argument is {@code null} */ static double call(@Nonnull final BiShortToDoubleFunction function, short value1, short value2) { Objects.requireNonNull(function); return function.applyAsDouble(value1, value2); } /** * Creates a {@link BiShortToDoubleFunction} which uses the {@code first} parameter of this one as argument for the * given {@link ShortToDoubleFunction}. * * @param function The function which accepts the {@code first} parameter of this one * @return Creates a {@code BiShortToDoubleFunction} which uses the {@code first} parameter of this one as argument * for the given {@code ShortToDoubleFunction}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull static BiShortToDoubleFunction onlyFirst(@Nonnull final ShortToDoubleFunction function) { Objects.requireNonNull(function); return (value1, value2) -> function.applyAsDouble(value1); } /** * Creates a {@link BiShortToDoubleFunction} which uses the {@code second} parameter of this one as argument for the * given {@link ShortToDoubleFunction}. * * @param function The function which accepts the {@code second} parameter of this one * @return Creates a {@code BiShortToDoubleFunction} which uses the {@code second} parameter of this one as argument * for the given {@code ShortToDoubleFunction}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull static BiShortToDoubleFunction onlySecond(@Nonnull final ShortToDoubleFunction function) { Objects.requireNonNull(function); return (value1, value2) -> function.applyAsDouble(value2); } /** * Creates a {@link BiShortToDoubleFunction} which always returns a given value. * * @param ret The return value for the constant * @return A {@code BiShortToDoubleFunction} which always returns a given value. */ @Nonnull static BiShortToDoubleFunction constant(double ret) { return (value1, value2) -> ret; } /** * Applies this function to the given arguments. * * @param value1 The first argument to the function * @param value2 The second argument to the function * @return The return value from the function, which is its result. */ double applyAsDouble(short value1, short value2); /** * Applies this function partially to some arguments of this one, producing a {@link ShortToDoubleFunction} as * result. * * @param value1 The first argument to this function used to partially apply this function * @return A {@code ShortToDoubleFunction} that represents this function partially applied the some arguments. */ @Nonnull default ShortToDoubleFunction papplyAsDouble(short value1) { return (value2) -> this.applyAsDouble(value1, value2); } /** * Returns the number of arguments for this function. * * @return The number of arguments for this function. * @implSpec The default implementation always returns {@code 2}. */ @Nonnegative default int arity() { return 2; } /** * Returns a composed {@link ToDoubleBiFunction2} that first applies the {@code before} functions to its input, and * then applies this function to the result. * If evaluation of either operation throws an exception, it is relayed to the caller of the composed operation. * * @param <A> The type of the argument to the first given function, and of composed function * @param <B> The type of the argument to the second given function, and of composed function * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code ToDoubleBiFunction2} that first applies the {@code before} functions to its input, and * then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is able to handle every type. */ @Nonnull default <A, B> ToDoubleBiFunction2<A, B> compose(@Nonnull final ToShortFunction<? super A> before1, @Nonnull final ToShortFunction<? super B> before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (a, b) -> applyAsDouble(before1.applyAsShort(a), before2.applyAsShort(b)); } /** * Returns a composed {@link BiBooleanToDoubleFunction} that first applies the {@code before} functions to its * input, and then applies this function to the result. If evaluation of either operation throws an exception, it is * relayed to the caller of the composed operation. This method is just convenience, to provide the ability to * execute an operation which accepts {@code boolean} input, before this primitive function is executed. * * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code BiBooleanToDoubleFunction} that first applies the {@code before} functions to its * input, and then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to handle primitive values. In this case this is {@code * boolean}. */ @Nonnull default BiBooleanToDoubleFunction composeFromBoolean(@Nonnull final BooleanToShortFunction before1, @Nonnull final BooleanToShortFunction before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (value1, value2) -> applyAsDouble(before1.applyAsShort(value1), before2.applyAsShort(value2)); } /** * Returns a composed {@link BiByteToDoubleFunction} that first applies the {@code before} functions to * its input, and then applies this function to the result. * If evaluation of either operation throws an exception, it is relayed to the caller of the composed operation. * This method is just convenience, to provide the ability to execute an operation which accepts {@code byte} input, * before this primitive function is executed. * * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code BiByteToDoubleFunction} that first applies the {@code before} functions to its input, * and then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to handle primitive values. In this case this is {@code * byte}. */ @Nonnull default BiByteToDoubleFunction composeFromByte(@Nonnull final ByteToShortFunction before1, @Nonnull final ByteToShortFunction before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (value1, value2) -> applyAsDouble(before1.applyAsShort(value1), before2.applyAsShort(value2)); } /** * Returns a composed {@link BiCharToDoubleFunction} that first applies the {@code before} functions to * its input, and then applies this function to the result. * If evaluation of either operation throws an exception, it is relayed to the caller of the composed operation. * This method is just convenience, to provide the ability to execute an operation which accepts {@code char} input, * before this primitive function is executed. * * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code BiCharToDoubleFunction} that first applies the {@code before} functions to its input, * and then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to handle primitive values. In this case this is {@code * char}. */ @Nonnull default BiCharToDoubleFunction composeFromChar(@Nonnull final CharToShortFunction before1, @Nonnull final CharToShortFunction before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (value1, value2) -> applyAsDouble(before1.applyAsShort(value1), before2.applyAsShort(value2)); } /** * Returns a composed {@link DoubleBinaryOperator2} that first applies the {@code before} functions to its input, * and then applies this function to the result. If evaluation of either operation throws an exception, it is * relayed to the caller of the composed operation. This method is just convenience, to provide the ability to * execute an operation which accepts {@code double} input, before this primitive function is executed. * * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code DoubleBinaryOperator2} that first applies the {@code before} functions to its input, * and then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to handle primitive values. In this case this is {@code * double}. */ @Nonnull default DoubleBinaryOperator2 composeFromDouble(@Nonnull final DoubleToShortFunction before1, @Nonnull final DoubleToShortFunction before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (value1, value2) -> applyAsDouble(before1.applyAsShort(value1), before2.applyAsShort(value2)); } /** * Returns a composed {@link BiFloatToDoubleFunction} that first applies the {@code before} functions to its input, * and then applies this function to the result. If evaluation of either operation throws an exception, it is * relayed to the caller of the composed operation. This method is just convenience, to provide the ability to * execute an operation which accepts {@code float} input, before this primitive function is executed. * * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code BiFloatToDoubleFunction} that first applies the {@code before} functions to its input, * and then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to handle primitive values. In this case this is {@code * float}. */ @Nonnull default BiFloatToDoubleFunction composeFromFloat(@Nonnull final FloatToShortFunction before1, @Nonnull final FloatToShortFunction before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (value1, value2) -> applyAsDouble(before1.applyAsShort(value1), before2.applyAsShort(value2)); } /** * Returns a composed {@link BiIntToDoubleFunction} that first applies the {@code before} functions to * its input, and then applies this function to the result. * If evaluation of either operation throws an exception, it is relayed to the caller of the composed operation. * This method is just convenience, to provide the ability to execute an operation which accepts {@code int} input, * before this primitive function is executed. * * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code BiIntToDoubleFunction} that first applies the {@code before} functions to its input, * and then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to handle primitive values. In this case this is {@code * int}. */ @Nonnull default BiIntToDoubleFunction composeFromInt(@Nonnull final IntToShortFunction before1, @Nonnull final IntToShortFunction before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (value1, value2) -> applyAsDouble(before1.applyAsShort(value1), before2.applyAsShort(value2)); } /** * Returns a composed {@link BiLongToDoubleFunction} that first applies the {@code before} functions to * its input, and then applies this function to the result. * If evaluation of either operation throws an exception, it is relayed to the caller of the composed operation. * This method is just convenience, to provide the ability to execute an operation which accepts {@code long} input, * before this primitive function is executed. * * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code BiLongToDoubleFunction} that first applies the {@code before} functions to its input, * and then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to handle primitive values. In this case this is {@code * long}. */ @Nonnull default BiLongToDoubleFunction composeFromLong(@Nonnull final LongToShortFunction before1, @Nonnull final LongToShortFunction before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (value1, value2) -> applyAsDouble(before1.applyAsShort(value1), before2.applyAsShort(value2)); } /** * Returns a composed {@link BiShortToDoubleFunction} that first applies the {@code before} operators to its input, * and then applies this function to the result. If evaluation of either operation throws an exception, it is * relayed to the caller of the composed operation. This method is just convenience, to provide the ability to * execute an operation which accepts {@code short} input, before this primitive function is executed. * * @param before1 The first operator to apply before this function is applied * @param before2 The second operator to apply before this function is applied * @return A composed {@code BiShortToDoubleFunction} that first applies the {@code before} operators to its input, * and then applies this function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to handle primitive values. In this case this is {@code * short}. */ @Nonnull default BiShortToDoubleFunction composeFromShort(@Nonnull final ShortUnaryOperator before1, @Nonnull final ShortUnaryOperator before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (value1, value2) -> applyAsDouble(before1.applyAsShort(value1), before2.applyAsShort(value2)); } /** * Returns a composed {@link BiShortFunction} that first applies this function to its input, and then applies the * {@code after} function to the result. * If evaluation of either operation throws an exception, it is relayed to the caller of the composed operation. * * @param <S> The type of return value from the {@code after} function, and of the composed function * @param after The function to apply after this function is applied * @return A composed {@code BiShortFunction} that first applies this function to its input, and then applies the * {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is able to return every type. */ @Nonnull default <S> BiShortFunction<S> andThen(@Nonnull final DoubleFunction<? extends S> after) { Objects.requireNonNull(after); return (value1, value2) -> after.apply(applyAsDouble(value1, value2)); } /** * Returns a composed {@link BiShortPredicate} that first applies this function to its input, and then applies the * {@code after} predicate to the result. If evaluation of either operation throws an exception, it is relayed to * the caller of the composed operation. This method is just convenience, to provide the ability to transform this * primitive function to an operation returning {@code boolean}. * * @param after The predicate to apply after this function is applied * @return A composed {@code BiShortPredicate} that first applies this function to its input, and then applies the * {@code after} predicate to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * boolean}. */ @Nonnull default BiShortPredicate andThenToBoolean(@Nonnull final DoublePredicate after) { Objects.requireNonNull(after); return (value1, value2) -> after.test(applyAsDouble(value1, value2)); } /** * Returns a composed {@link BiShortToByteFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to * the caller of the composed operation. This method is just convenience, to provide the ability to transform this * primitive function to an operation returning {@code byte}. * * @param after The function to apply after this function is applied * @return A composed {@code BiShortToByteFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * byte}. */ @Nonnull default BiShortToByteFunction andThenToByte(@Nonnull final DoubleToByteFunction after) { Objects.requireNonNull(after); return (value1, value2) -> after.applyAsByte(applyAsDouble(value1, value2)); } /** * Returns a composed {@link BiShortToCharFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to * the caller of the composed operation. This method is just convenience, to provide the ability to transform this * primitive function to an operation returning {@code char}. * * @param after The function to apply after this function is applied * @return A composed {@code BiShortToCharFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * char}. */ @Nonnull default BiShortToCharFunction andThenToChar(@Nonnull final DoubleToCharFunction after) { Objects.requireNonNull(after); return (value1, value2) -> after.applyAsChar(applyAsDouble(value1, value2)); } /** * Returns a composed {@link BiShortToDoubleFunction} that first applies this function to its input, and then * applies the {@code after} operator to the result. If evaluation of either operation throws an exception, it is * relayed to the caller of the composed operation. This method is just convenience, to provide the ability to * transform this primitive function to an operation returning {@code double}. * * @param after The operator to apply after this function is applied * @return A composed {@code BiShortToDoubleFunction} that first applies this function to its input, and then * applies the {@code after} operator to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * double}. */ @Nonnull default BiShortToDoubleFunction andThenToDouble(@Nonnull final DoubleUnaryOperator after) { Objects.requireNonNull(after); return (value1, value2) -> after.applyAsDouble(applyAsDouble(value1, value2)); } /** * Returns a composed {@link BiShortToFloatFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to * the caller of the composed operation. This method is just convenience, to provide the ability to transform this * primitive function to an operation returning {@code float}. * * @param after The function to apply after this function is applied * @return A composed {@code BiShortToFloatFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * float}. */ @Nonnull default BiShortToFloatFunction andThenToFloat(@Nonnull final DoubleToFloatFunction after) { Objects.requireNonNull(after); return (value1, value2) -> after.applyAsFloat(applyAsDouble(value1, value2)); } /** * Returns a composed {@link BiShortToIntFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to * the caller of the composed operation. This method is just convenience, to provide the ability to transform this * primitive function to an operation returning {@code int}. * * @param after The function to apply after this function is applied * @return A composed {@code BiShortToIntFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * int}. */ @Nonnull default BiShortToIntFunction andThenToInt(@Nonnull final DoubleToIntFunction after) { Objects.requireNonNull(after); return (value1, value2) -> after.applyAsInt(applyAsDouble(value1, value2)); } /** * Returns a composed {@link BiShortToLongFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to * the caller of the composed operation. This method is just convenience, to provide the ability to transform this * primitive function to an operation returning {@code long}. * * @param after The function to apply after this function is applied * @return A composed {@code BiShortToLongFunction} that first applies this function to its input, and then applies * the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * long}. */ @Nonnull default BiShortToLongFunction andThenToLong(@Nonnull final DoubleToLongFunction after) { Objects.requireNonNull(after); return (value1, value2) -> after.applyAsLong(applyAsDouble(value1, value2)); } /** * Returns a composed {@link ShortBinaryOperator} that first applies this function to its input, and then applies * the {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to * the caller of the composed operation. This method is just convenience, to provide the ability to transform this * primitive function to an operation returning {@code short}. * * @param after The function to apply after this function is applied * @return A composed {@code ShortBinaryOperator} that first applies this function to its input, and then applies * the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * short}. */ @Nonnull default ShortBinaryOperator andThenToShort(@Nonnull final DoubleToShortFunction after) { Objects.requireNonNull(after); return (value1, value2) -> after.applyAsShort(applyAsDouble(value1, value2)); } /** * Returns a composed {@link BiShortConsumer} that fist applies this function to its input, and then consumes the * result using the given {@link DoubleConsumer}. If evaluation of either operation throws an exception, it is * relayed to the caller of the composed operation. * * @param consumer The operation which consumes the result from this operation * @return A composed {@code BiShortConsumer} that first applies this function to its input, and then consumes the * result using the given {@code DoubleConsumer}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull default BiShortConsumer consume(@Nonnull final DoubleConsumer consumer) { Objects.requireNonNull(consumer); return (value1, value2) -> consumer.accept(applyAsDouble(value1, value2)); } /** * Returns a memoized (caching) version of this {@link BiShortToDoubleFunction}. Whenever it is called, the mapping * between the input parameters and the return value is preserved in a cache, making subsequent calls returning the * memoized value instead of computing the return value again. * <p> * Unless the function and therefore the used cache will be garbage-collected, it will keep all memoized values * forever. * * @return A memoized (caching) version of this {@code BiShortToDoubleFunction}. * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the * resulting memoized function, as the cache used internally does not permit {@code null} keys or values. * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it * thread-safe. */ @Nonnull default BiShortToDoubleFunction memoized() { if (isMemoized()) { return this; } else { final Map<Pair<Short, Short>, Double> cache = new ConcurrentHashMap<>(); final Object lock = new Object(); return (BiShortToDoubleFunction & Memoized) (value1, value2) -> { final double returnValue; synchronized (lock) { returnValue = cache.computeIfAbsent(Pair.of(value1, value2), key -> applyAsDouble(key.getLeft(), key.getRight())); } return returnValue; }; } } /** * Returns a composed {@link BiFunction2} which represents this {@link BiShortToDoubleFunction}. Thereby the * primitive input argument for this function is autoboxed. This method provides the possibility to use this {@code * BiShortToDoubleFunction} with methods provided by the {@code JDK}. * * @return A composed {@code BiFunction2} which represents this {@code BiShortToDoubleFunction}. */ @Nonnull default BiFunction2<Short, Short, Double> boxed() { return this::applyAsDouble; } }