From eb6b3704d0bdfc04d0d862d38140c100da2c09d5 Mon Sep 17 00:00:00 2001
From: dfsek <dfsek@dfsek.com>
Date: Thu, 1 Jan 2026 20:09:06 -0700
Subject: [PATCH] add linkedlist

---
 .../api/util/generic/data/LinkedList.java     | 143 +++++++++++++
 .../terra/api/util/generic/data/Monoid.java   |   7 +-
 .../api/util/generic/data/Semigroup.java      |   8 -
 .../api/util/generic/data/types/Either.java   | 199 +++++++++---------
 .../api/util/generic/data/types/Maybe.java    | 165 ++++++++-------
 5 files changed, 334 insertions(+), 188 deletions(-)
 create mode 100644 common/api/src/main/java/com/dfsek/terra/api/util/generic/data/LinkedList.java
 delete mode 100644 common/api/src/main/java/com/dfsek/terra/api/util/generic/data/Semigroup.java

diff --git a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/LinkedList.java b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/LinkedList.java
new file mode 100644
index 000000000..a14c925ce
--- /dev/null
+++ b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/LinkedList.java
@@ -0,0 +1,143 @@
+package com.dfsek.terra.api.util.generic.data;
+
+import com.dfsek.terra.api.util.generic.control.Monad;
+import com.dfsek.terra.api.util.generic.data.types.Maybe;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.function.Function;
+
+
+public sealed interface LinkedList<T> extends Monad<T, LinkedList<?>>, Monoid<T, LinkedList<?>> {
+    @Override
+    <T2> LinkedList<T2> bind(Function<T, Monad<T2, LinkedList<?>>> map);
+
+    @Override
+    default <T1> LinkedList<T1> pure(T1 t) {
+        return new Cons<>(t, empty());
+    }
+
+    @Override
+    <U> LinkedList<U> map(Function<T, U> map);
+
+    @Override
+    default <T1> LinkedList<T1> identity() {
+        return empty();
+    }
+
+    default Maybe<T> head() {
+        return get(0);
+    }
+
+    int length();
+
+    Maybe<T> get(int index);
+
+    LinkedList<T> add(T value);
+
+    <C extends Collection<T>> C toCollection(C collection);
+
+    default List<T> toList() {
+        return toCollection(new ArrayList<>());
+    }
+
+    default Set<T> toSet() {
+        return toCollection(new HashSet<>());
+    }
+
+    @Override
+    LinkedList<T> multiply(Monoid<T, LinkedList<?>> t);
+
+    static <T> LinkedList<T> of(T value) {
+        return new Cons<>(value, empty());
+    }
+
+    @SuppressWarnings("unchecked")
+    static <T> Nil<T> empty() {
+        return (Nil<T>) Nil.INSTANCE;
+    }
+
+    record Cons<T>(T value, LinkedList<T> tail) implements LinkedList<T> {
+        @Override
+        public <T2> LinkedList<T2> bind(Function<T, Monad<T2, LinkedList<?>>> map) {
+            return ((LinkedList<T2>) map.apply(value)).multiply(tail.bind(map));
+        }
+
+        @Override
+        public <U> LinkedList<U> map(Function<T, U> map) {
+            return new Cons<>(map.apply(value), tail.map(map));
+        }
+
+        @Override
+        public int length() {
+            return 1 + tail.length();
+        }
+
+        @Override
+        public Maybe<T> get(int index) {
+            if(index == 0) return Maybe.just(value);
+            if(index > 0) return Maybe.nothing();
+            return tail.get(index - 1);
+        }
+
+        @Override
+        public LinkedList<T> add(T value) {
+            return new Cons<>(value, tail.add(value));
+        }
+
+        @Override
+        public <C extends Collection<T>> C toCollection(C collection) {
+            collection.add(value);
+            return tail.toCollection(collection);
+        }
+
+        @Override
+        public LinkedList<T> multiply(Monoid<T, LinkedList<?>> t) {
+            return new Cons<>(value, tail.multiply(t));
+        }
+    }
+
+    record Nil<T>() implements LinkedList<T> {
+        private static final Nil<?> INSTANCE = new Nil<>();
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public <T2> LinkedList<T2> bind(Function<T, Monad<T2, LinkedList<?>>> map) {
+            return (LinkedList<T2>) this;
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public <U> LinkedList<U> map(Function<T, U> map) {
+            return (LinkedList<U>) this;
+        }
+
+        @Override
+        public int length() {
+            return 0;
+        }
+
+        @Override
+        public Maybe<T> get(int index) {
+            return Maybe.nothing();
+        }
+
+        @Override
+        public LinkedList<T> add(T value) {
+            return new Cons<>(value, empty());
+        }
+
+        @Override
+        public <C extends Collection<T>> C toCollection(C collection) {
+            return collection;
+        }
+
+        @Override
+        public LinkedList<T> multiply(Monoid<T, LinkedList<?>> t) {
+            return (LinkedList<T>) t;
+        }
+    }
+}
diff --git a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/Monoid.java b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/Monoid.java
index 7725067b8..ed5fb2334 100644
--- a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/Monoid.java
+++ b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/Monoid.java
@@ -3,9 +3,8 @@ package com.dfsek.terra.api.util.generic.data;
 import com.dfsek.terra.api.util.generic.kinds.K;
 
 
-public interface Monoid<T, M extends Monoid<?, M>> extends Semigroup<T, M>, K<M, T>{
-    <T1, M1 extends Monoid<?, M1>> Monoid<T1, M1> identity();
+public interface Monoid<T, M extends Monoid<?, M>> extends K<M, T>{
+    <T1> Monoid<T1, M> identity();
 
-    @Override
-    Monoid<T, M> multiply(M t);
+    Monoid<T, M> multiply(Monoid<T, M> t);
 }
diff --git a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/Semigroup.java b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/Semigroup.java
deleted file mode 100644
index 26ec7f36f..000000000
--- a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/Semigroup.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package com.dfsek.terra.api.util.generic.data;
-
-import com.dfsek.terra.api.util.generic.kinds.K;
-
-
-public interface Semigroup<T, S extends Semigroup<?, S>> extends K<S, T> {
-    Semigroup<T, S> multiply(S t);
-}
diff --git a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/types/Either.java b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/types/Either.java
index 19291b4a7..37d1e11cc 100644
--- a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/types/Either.java
+++ b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/types/Either.java
@@ -21,7 +21,7 @@ import java.util.function.Consumer;
 import java.util.function.Function;
 
 
-public interface Either<L, R> extends Monad<R, Either<?, ?>>, BiFunctor<L, R, Either<?, ?>> {
+public sealed interface Either<L, R> extends Monad<R, Either<?, ?>>, BiFunctor<L, R, Either<?, ?>> {
     default Either<L, R> ifLeft(Consumer<L> action) {
         return mapLeft(FunctionUtils.lift(action));
     }
@@ -77,115 +77,114 @@ public interface Either<L, R> extends Monad<R, Either<?, ?>>, BiFunctor<L, R, Ei
         return mapLeft(left).collect(l -> FunctionUtils.sneakyThrow(l), Function.identity());
     }
 
-    @SuppressWarnings({ "unchecked" })
     @NotNull
     @Contract("_ -> new")
     static <L1, R1> Either<L1, R1> left(L1 left) {
-        record Left<L, R>(L value) implements Either<L, R> {
-
-            @Override
-            @SuppressWarnings("unchecked")
-            public <T2> Either<L, T2> bind(Function<R, Monad<T2, Either<?, ?>>> map) {
-                return (Either<L, T2>) this;
-            }
-
-            @Override
-            public <L1> Either<L1, R> mapLeft(Function<L, L1> f) {
-                return new Left<>(f.apply(value));
-            }
-
-            @SuppressWarnings({ "unchecked" })
-            @Override
-            public <R1> Either<L, R1> mapRight(Function<R, R1> f) {
-                return (Either<L, R1>) this;
-            }
-
-            @Override
-            public Maybe<L> getLeft() {
-                return Maybe.just(value);
-            }
-
-            @Override
-            public Maybe<R> getRight() {
-                return Maybe.nothing();
-            }
-
-            @Override
-            public boolean isLeft() {
-                return true;
-            }
-
-            @Override
-            public boolean isRight() {
-                return false;
-            }
-
-            @Override
-            public Either<R, L> flip() {
-                return right(value);
-            }
-
-            @Override
-            public <U> U collect(Function<L, U> left, Function<R, U> right) {
-                return left.apply(value);
-            }
-        }
-
         return new Left<>(Objects.requireNonNull(left));
     }
 
-    @SuppressWarnings({ "unchecked" })
     @NotNull
     @Contract("_ -> new")
     static <L1, R1> Either<L1, R1> right(R1 right) {
-        record Right<L, R>(R value) implements Either<L, R> {
-            @Override
-            public <T2> Either<L, T2> bind(Function<R, Monad<T2, Either<?, ?>>> map) {
-                return (Either<L, T2>) map.apply(value);
-            }
-
-            @SuppressWarnings({ "unchecked" })
-            @Override
-            public <L1> Either<L1, R> mapLeft(Function<L, L1> f) {
-                return (Either<L1, R>) this;
-            }
-
-            @Override
-            public <R1> Either<L, R1> mapRight(Function<R, R1> f) {
-                return new Right<>(f.apply(value));
-            }
-
-            @Override
-            public Maybe<L> getLeft() {
-                return Maybe.nothing();
-            }
-
-            @Override
-            public Maybe<R> getRight() {
-                return Maybe.just(value);
-            }
-
-            @Override
-            public boolean isLeft() {
-                return false;
-            }
-
-            @Override
-            public boolean isRight() {
-                return true;
-            }
-
-            @Override
-            public Either<R, L> flip() {
-                return left(value);
-            }
-
-            @Override
-            public <U> U collect(Function<L, U> left, Function<R, U> right) {
-                return right.apply(value);
-            }
-        }
         return new Right<>(Objects.requireNonNull(right));
     }
 
+    record Left<L, R>(L value) implements Either<L, R> {
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public <T2> Either<L, T2> bind(Function<R, Monad<T2, Either<?, ?>>> map) {
+            return (Either<L, T2>) this;
+        }
+
+        @Override
+        public <L1> Either<L1, R> mapLeft(Function<L, L1> f) {
+            return new Left<>(f.apply(value));
+        }
+
+        @SuppressWarnings({ "unchecked" })
+        @Override
+        public <R1> Either<L, R1> mapRight(Function<R, R1> f) {
+            return (Either<L, R1>) this;
+        }
+
+        @Override
+        public Maybe<L> getLeft() {
+            return Maybe.just(value);
+        }
+
+        @Override
+        public Maybe<R> getRight() {
+            return Maybe.nothing();
+        }
+
+        @Override
+        public boolean isLeft() {
+            return true;
+        }
+
+        @Override
+        public boolean isRight() {
+            return false;
+        }
+
+        @Override
+        public Either<R, L> flip() {
+            return right(value);
+        }
+
+        @Override
+        public <U> U collect(Function<L, U> left, Function<R, U> right) {
+            return left.apply(value);
+        }
+    }
+
+
+    record Right<L, R>(R value) implements Either<L, R> {
+        @Override
+        public <T2> Either<L, T2> bind(Function<R, Monad<T2, Either<?, ?>>> map) {
+            return (Either<L, T2>) map.apply(value);
+        }
+
+        @SuppressWarnings({ "unchecked" })
+        @Override
+        public <L1> Either<L1, R> mapLeft(Function<L, L1> f) {
+            return (Either<L1, R>) this;
+        }
+
+        @Override
+        public <R1> Either<L, R1> mapRight(Function<R, R1> f) {
+            return new Right<>(f.apply(value));
+        }
+
+        @Override
+        public Maybe<L> getLeft() {
+            return Maybe.nothing();
+        }
+
+        @Override
+        public Maybe<R> getRight() {
+            return Maybe.just(value);
+        }
+
+        @Override
+        public boolean isLeft() {
+            return false;
+        }
+
+        @Override
+        public boolean isRight() {
+            return true;
+        }
+
+        @Override
+        public Either<R, L> flip() {
+            return left(value);
+        }
+
+        @Override
+        public <U> U collect(Function<L, U> left, Function<R, U> right) {
+            return right.apply(value);
+        }
+    }
 }
\ No newline at end of file
diff --git a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/types/Maybe.java b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/types/Maybe.java
index cbd981f75..7aa1b683e 100644
--- a/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/types/Maybe.java
+++ b/common/api/src/main/java/com/dfsek/terra/api/util/generic/data/types/Maybe.java
@@ -1,6 +1,7 @@
 package com.dfsek.terra.api.util.generic.data.types;
 
 import com.dfsek.terra.api.util.generic.control.Monad;
+import com.dfsek.terra.api.util.generic.data.LinkedList;
 
 import java.util.NoSuchElementException;
 import java.util.Optional;
@@ -11,7 +12,7 @@ import java.util.function.Supplier;
 import java.util.stream.Stream;
 
 
-public interface Maybe<T> extends Monad<T, Maybe<?>> {
+public sealed interface Maybe<T> extends Monad<T, Maybe<?>> {
     @Override
     default <T1> Maybe<T1> pure(T1 t) {
         return just(t);
@@ -49,9 +50,20 @@ public interface Maybe<T> extends Monad<T, Maybe<?>> {
         return this;
     }
 
+    default Maybe<T> collapse(Runnable nothing, Consumer<T> just) {
+        return consume(just).ifNothing(nothing);
+    }
+
+
+    default LinkedList<T> toList() {
+        return map(LinkedList::of).get(LinkedList::empty);
+    }
 
     /**
      * Project a new value into this Maybe if it is Nothing.
+     * Effectively a bind operation over Nothing, treating it as a Void type.
+     * <p>
+     * Converse of {@link #bind}.
      */
     Maybe<T> or(Supplier<Maybe<T>> or);
 
@@ -59,7 +71,6 @@ public interface Maybe<T> extends Monad<T, Maybe<?>> {
         return or(() -> just(or.get()));
     }
 
-
     @Deprecated
     default <X extends Throwable> T orThrow() {
         return get(() -> { throw new NoSuchElementException("No value present."); });
@@ -73,7 +84,6 @@ public interface Maybe<T> extends Monad<T, Maybe<?>> {
         throw e.get();
     }
 
-
     default Maybe<T> or(Maybe<T> or) {
         return or(() -> or);
     }
@@ -96,85 +106,88 @@ public interface Maybe<T> extends Monad<T, Maybe<?>> {
     }
 
     static <T1> Maybe<T1> just(T1 t) {
-        record Just<T>(T value) implements Maybe<T> {
 
-            @Override
-            public Optional<T> toOptional() {
-                return Optional.of(value);
-            }
-
-            @Override
-            public <L> Either<L, T> toEither(L l) {
-                return Either.right(value);
-            }
-
-            @Override
-            public T get(Supplier<T> def) {
-                return value;
-            }
-
-            @Override
-            public boolean isJust() {
-                return true;
-            }
-
-            @Override
-            public <U> Maybe<U> map(Function<T, U> map) {
-                return just(map.apply(value));
-            }
-
-            @Override
-            public Maybe<T> or(Supplier<Maybe<T>> or) {
-                return this;
-            }
-
-            @Override
-            public <T2> Maybe<T2> bind(Function<T, Monad<T2, Maybe<?>>> map) {
-                return (Maybe<T2>) map.apply(value);
-            }
-        }
         return new Just<>(t);
     }
 
     static <T1> Maybe<T1> nothing() {
-        record Nothing<T>() implements Maybe<T> {
 
-            @Override
-            public <T2> Maybe<T2> bind(Function<T, Monad<T2, Maybe<?>>> map) {
-                return nothing();
-            }
-
-            @Override
-            public Optional<T> toOptional() {
-                return Optional.empty();
-            }
-
-            @Override
-            public <L> Either<L, T> toEither(L l) {
-                return Either.left(l);
-            }
-
-            @Override
-            public T get(Supplier<T> def) {
-                return def.get();
-            }
-
-            @Override
-            public boolean isJust() {
-                return false;
-            }
-
-            @Override
-            @SuppressWarnings("unchecked")
-            public <U> Maybe<U> map(Function<T, U> map) {
-                return (Maybe<U>) this;
-            }
-
-            @Override
-            public Maybe<T> or(Supplier<Maybe<T>> or) {
-                return or.get();
-            }
-        }
         return new Nothing<>();
     }
+
+    record Just<T>(T value) implements Maybe<T> {
+        @Override
+        public Optional<T> toOptional() {
+            return Optional.of(value);
+        }
+
+        @Override
+        public <L> Either<L, T> toEither(L l) {
+            return Either.right(value);
+        }
+
+        @Override
+        public T get(Supplier<T> def) {
+            return value;
+        }
+
+        @Override
+        public boolean isJust() {
+            return true;
+        }
+
+        @Override
+        public <U> Maybe<U> map(Function<T, U> map) {
+            return just(map.apply(value));
+        }
+
+        @Override
+        public Maybe<T> or(Supplier<Maybe<T>> or) {
+            return this;
+        }
+
+        @Override
+        public <T2> Maybe<T2> bind(Function<T, Monad<T2, Maybe<?>>> map) {
+            return (Maybe<T2>) map.apply(value);
+        }
+    }
+
+
+    record Nothing<T>() implements Maybe<T> {
+        @Override
+        public <T2> Maybe<T2> bind(Function<T, Monad<T2, Maybe<?>>> map) {
+            return nothing();
+        }
+
+        @Override
+        public Optional<T> toOptional() {
+            return Optional.empty();
+        }
+
+        @Override
+        public <L> Either<L, T> toEither(L l) {
+            return Either.left(l);
+        }
+
+        @Override
+        public T get(Supplier<T> def) {
+            return def.get();
+        }
+
+        @Override
+        public boolean isJust() {
+            return false;
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public <U> Maybe<U> map(Function<T, U> map) {
+            return (Maybe<U>) this;
+        }
+
+        @Override
+        public Maybe<T> or(Supplier<Maybe<T>> or) {
+            return or.get();
+        }
+    }
 }