General changes

3 files changed, 112 insertions, 0 deletions

diff --git a/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Bifunctor.java b/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Bifunctor.java
new file mode 100644
index 0000000..3bea135
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Bifunctor.java
@@ -0,0 +1,66 @@
+package bjc.utils.funcdata.theory;
+
+import java.util.function.Function;
+
+/**
+ * A functor over a pair of heterogenous types
+ * 
+ * @author ben
+ * @param <LeftType>
+ *            The type stored on the 'left' of the pair
+ * @param <RightType>
+ *            The type stored on the 'right' of the pair
+ *
+ */
+public interface Bifunctor<LeftType, RightType> {
+	/**
+	 * Lift a function to operate over the left part of this pair
+	 * 
+	 * @param <OldLeft>
+	 *            The old left type of the pair
+	 * @param <OldRight>
+	 *            The old right type of the pair
+	 * @param <NewLeft>
+	 *            The new left type of the pair
+	 * @param func
+	 *            The function to lift to work over the left side of the
+	 *            pair
+	 * @return The function lifted to work over the left side of bifunctors
+	 */
+	public <OldLeft, OldRight, NewLeft>
+			Function<Bifunctor<OldLeft, OldRight>, Bifunctor<NewLeft, OldRight>>
+			fmapLeft(Function<OldLeft, NewLeft> func);
+
+	/**
+	 * Lift a function to operate over the right part of this pair
+	 * 
+	 * @param <OldLeft>
+	 *            The old left type of the pair
+	 * @param <OldRight>
+	 *            The old right type of the pair
+	 * @param <NewRight>
+	 *            The new right type of the pair
+	 * @param func
+	 *            The function to lift to work over the right side of the
+	 *            pair
+	 * @return The function lifted to work over the right side of
+	 *         bifunctors
+	 */
+	public <OldLeft, OldRight, NewRight>
+			Function<Bifunctor<OldLeft, OldRight>, Bifunctor<OldLeft, NewRight>>
+			fmapRight(Function<OldRight, NewRight> func);
+
+	/**
+	 * Get the value contained on the left of this bifunctor
+	 * 
+	 * @return The value on the left side of this bifunctor
+	 */
+	public LeftType getLeft();
+
+	/**
+	 * Get the value contained on the right of this bifunctor
+	 * 
+	 * @return The value on the right of this bifunctor
+	 */
+	public RightType getRight();
+}
diff --git a/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Functor.java b/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Functor.java
new file mode 100644
index 0000000..76f48e2
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Functor.java
@@ -0,0 +1,39 @@
+package bjc.utils.funcdata.theory;
+
+import java.util.function.Function;
+
+/**
+ * Represents a container or context some sort usually, but the precise
+ * definition is that it represents exactly what it is defined as
+ * 
+ * @author ben
+ * @param <ContainedType>
+ *            The value inside the functor
+ */
+public interface Functor<ContainedType> {
+	/**
+	 * Converts a normal function to operate over values in a functor.
+	 * 
+	 * N.B: Even though the type signature implies that you can apply the
+	 * resulting function to any type of functor, it is only safe to call
+	 * it on instances of the type of functor you called fmap on.
+	 * 
+	 * @param <ArgType>
+	 *            The argument of the function
+	 * @param <ReturnType>
+	 *            The return type of the function
+	 * @param func
+	 *            The function to convert
+	 * @return The passed in function converted to work over a particular
+	 *         type of functors
+	 */
+	public <ArgType, ReturnType> Function<Functor<ArgType>, Functor<ReturnType>> fmap(
+			Function<ArgType, ReturnType> func);
+
+	/**
+	 * Retrieve the thing inside this functor
+	 * 
+	 * @return The thing inside this functor
+	 */
+	public ContainedType getValue();
+}
diff --git a/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/package-info.java b/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/package-info.java
new file mode 100644
index 0000000..33c80d6
--- /dev/null
+++ b/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/package-info.java
@@ -0,0 +1,7 @@
+/**
+ * Random functional type things that don't belong elsewhere
+ * 
+ * @author ben
+ *
+ */
+package bjc.utils.funcdata.theory;
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