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ADT codegen reference
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| import java.util.function.Function; | |
| public interface Adt { | |
| static void main(String[] args) { | |
| map(OptionOf.some(100), String::valueOf).match(new Option<String>() { | |
| @Override | |
| public void none() { | |
| System.out.println("NONE!"); | |
| } | |
| @Override | |
| public void some(String t) { | |
| System.out.println(t); | |
| } | |
| }); | |
| } | |
| static <T, U> OptionOf<U> map(OptionOf<T> tOption, Function<T, U> f) { | |
| return tOption.match(new OptionTo<T, OptionOf<U>>() { | |
| @Override | |
| public OptionOf<U> none() { | |
| return OptionOf.none(); | |
| } | |
| @Override | |
| public OptionOf<U> some(T t) { | |
| return OptionOf.some(f.apply(t)); | |
| } | |
| }); | |
| } | |
| } | |
| // @Case | |
| interface Option<T> { | |
| void none(); | |
| void some(T t); | |
| } | |
| // everything below can be generated from the case interface | |
| interface OptionTo<T, U> { | |
| U none(); | |
| U some(T t); | |
| } | |
| abstract class OptionOr<T> implements Option<T> { | |
| public abstract void orElse(); | |
| @Override | |
| public void none() { | |
| orElse(); | |
| } | |
| @Override | |
| public void some(T t) { | |
| orElse(); | |
| } | |
| } | |
| abstract class OptionOrTo<T, U> implements OptionTo<T, U> { | |
| public abstract U orElse(); | |
| @Override | |
| public U none() { | |
| return orElse(); | |
| } | |
| @Override | |
| public U some(T t) { | |
| return orElse(); | |
| } | |
| } | |
| abstract class OptionOf<T> { | |
| private OptionOf() {} | |
| public abstract void match(Option<T> of); | |
| public static <T> OptionOf<T> none() { | |
| return new OptionOf<T>() { | |
| @Override | |
| public void match(Option<T> of) { | |
| of.none(); | |
| } | |
| }; | |
| } | |
| public static <T> OptionOf<T> some(final T t) { | |
| return new OptionOf<T>() { | |
| @Override | |
| public void match(Option<T> of) { | |
| of.some(t); | |
| } | |
| }; | |
| } | |
| public <U> U match(final OptionTo<T, U> to) { | |
| return new Option<T>() { | |
| U u; { | |
| match(this); | |
| } | |
| @Override | |
| public void none() { | |
| u = to.none(); | |
| } | |
| @Override | |
| public void some(T t) { | |
| u = to.some(t); | |
| } | |
| }.u; | |
| } | |
| } |
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