diff --git a/eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/meta/EnchantmentType.java b/eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/meta/EnchantmentType.java
index f3c8391f..5f96d31b 100644
--- a/eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/meta/EnchantmentType.java
+++ b/eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/meta/EnchantmentType.java
@@ -3,7 +3,6 @@ package com.willfp.ecoenchants.enchantments.meta;
 import com.google.common.collect.ImmutableList;
 import com.willfp.eco.util.config.Configs;
 import com.willfp.eco.util.config.annotations.ConfigUpdater;
-import com.willfp.eco.util.lambda.ObjectCallable;
 import com.willfp.ecoenchants.enchantments.EcoEnchant;
 import com.willfp.ecoenchants.enchantments.itemtypes.Artifact;
 import com.willfp.ecoenchants.enchantments.itemtypes.Spell;
@@ -13,6 +12,7 @@ import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Supplier;
 
 public class EnchantmentType {
     /**
@@ -80,12 +80,12 @@ public class EnchantmentType {
     /**
      * Lambda to fetch the color of the type.
      */
-    private final ObjectCallable<String> colorCallable;
+    private final Supplier<String> colorSupplier;
 
     /**
      * Lambda to fetch the singularity of the type.
      */
-    private final ObjectCallable<Boolean> singularCallable;
+    private final Supplier<Boolean> singularSupplier;
 
     /**
      * If only one enchantment of this type is allowed on an item.
@@ -136,12 +136,12 @@ public class EnchantmentType {
      *
      * @param name          The name of the type.
      * @param singular      Whether an item can have several enchantments of this type.
-     * @param colorCallable Lambda to fetch the color of enchantments with this type to have. Updates on /ecoreload.
+     * @param colorSupplier Lambda to fetch the color of enchantments with this type to have. Updates on /ecoreload.
      */
     public EnchantmentType(@NotNull final String name,
                            final boolean singular,
-                           @NotNull final ObjectCallable<String> colorCallable) {
-        this(name, () -> singular, colorCallable);
+                           @NotNull final Supplier<String> colorSupplier) {
+        this(name, () -> singular, colorSupplier);
     }
 
     /**
@@ -151,57 +151,57 @@ public class EnchantmentType {
      *
      * @param name             The name of the type.
      * @param singular         Whether an item can have several enchantments of this type.
-     * @param colorCallable    Lambda to fetch the color of enchantments with this type to have. Updates on /ecoreload.
+     * @param colorSupplier    Lambda to fetch the color of enchantments with this type to have. Updates on /ecoreload.
      * @param requiredToExtend Class that all enchantments of this type must extend - or null if not required.
      */
     public EnchantmentType(@NotNull final String name,
                            final boolean singular,
-                           @NotNull final ObjectCallable<String> colorCallable,
+                           @NotNull final Supplier<String> colorSupplier,
                            @Nullable final Class<? extends EcoEnchant> requiredToExtend) {
-        this(name, () -> singular, colorCallable, requiredToExtend);
+        this(name, () -> singular, colorSupplier, requiredToExtend);
     }
 
     /**
      * Create EnchantmentType with updatable color and singularity.
      *
      * @param name             The name of the type.
-     * @param singularCallable Lambda to fetch whether an item can have several enchantments of this type. Updates on /ecoreload.
-     * @param colorCallable    Lambda to fetch the color of enchantments with this type to have. Updates on /ecoreload.
+     * @param singularSupplier Lambda to fetch whether an item can have several enchantments of this type. Updates on /ecoreload.
+     * @param colorSupplier    Lambda to fetch the color of enchantments with this type to have. Updates on /ecoreload.
      */
     public EnchantmentType(@NotNull final String name,
-                           @NotNull final ObjectCallable<Boolean> singularCallable,
-                           @NotNull final ObjectCallable<String> colorCallable) {
-        this(name, singularCallable, colorCallable, null);
+                           @NotNull final Supplier<Boolean> singularSupplier,
+                           @NotNull final Supplier<String> colorSupplier) {
+        this(name, singularSupplier, colorSupplier, null);
     }
 
     /**
      * Create EnchantmentType with updatable color and singularity that <b>must</b> extend a specified class.
      *
      * @param name             The name of the type.
-     * @param singularCallable Lambda to fetch whether an item can have several enchantments of this type. Updates on /ecoreload.
-     * @param colorCallable    Lambda to fetch the color of enchantments with this type to have. Updates on /ecoreload.
+     * @param singularSupplier Lambda to fetch whether an item can have several enchantments of this type. Updates on /ecoreload.
+     * @param colorSupplier    Lambda to fetch the color of enchantments with this type to have. Updates on /ecoreload.
      * @param requiredToExtend Class that all enchantments of this type must extend - or null if not required.
      */
     public EnchantmentType(@NotNull final String name,
-                           @NotNull final ObjectCallable<Boolean> singularCallable,
-                           @NotNull final ObjectCallable<String> colorCallable,
+                           @NotNull final Supplier<Boolean> singularSupplier,
+                           @NotNull final Supplier<String> colorSupplier,
                            @Nullable final Class<? extends EcoEnchant> requiredToExtend) {
         this.name = name;
-        this.singularCallable = singularCallable;
-        this.colorCallable = colorCallable;
+        this.singularSupplier = singularSupplier;
+        this.colorSupplier = colorSupplier;
         this.requiredToExtend = requiredToExtend;
-        color = colorCallable.call();
-        singular = singularCallable.call();
+        color = colorSupplier.get();
+        singular = singularSupplier.get();
         REGISTERED.add(this);
     }
 
     private void refresh() {
-        this.color = colorCallable.call();
-        this.singular = singularCallable.call();
+        this.color = colorSupplier.get();
+        this.singular = singularSupplier.get();
     }
 
     /**
-     * Update callables of all types.
+     * Update suppliers of all types.
      */
     @ConfigUpdater
     public static void update() {
diff --git a/eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/util/SpellRunnable.java b/eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/util/SpellRunnable.java
index 861f345c..65c8522c 100644
--- a/eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/util/SpellRunnable.java
+++ b/eco-core/core-plugin/src/main/java/com/willfp/ecoenchants/enchantments/util/SpellRunnable.java
@@ -1,7 +1,6 @@
 package com.willfp.ecoenchants.enchantments.util;
 
 
-import com.willfp.eco.util.lambda.Callable;
 import com.willfp.ecoenchants.enchantments.itemtypes.Spell;
 import lombok.Getter;
 import lombok.Setter;
@@ -32,7 +31,7 @@ public class SpellRunnable {
      * Must be set before execution.
      */
     @Setter
-    private Callable task = () -> {
+    private Runnable task = () -> {
         // Empty as must be set using this#setTask
     };
 
@@ -52,7 +51,7 @@ public class SpellRunnable {
      * Run the runnable.
      */
     public void run() {
-        task.call();
+        task.run();
         updateEndTime();
     }
 
diff --git a/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/EcoScheduler.java b/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/EcoScheduler.java
index 0c694d0b..6f0bbd19 100644
--- a/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/EcoScheduler.java
+++ b/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/EcoScheduler.java
@@ -1,7 +1,6 @@
 package com.willfp.eco.util.bukkit.scheduling;
 
 import com.willfp.eco.util.injection.PluginDependent;
-import com.willfp.eco.util.lambda.Callable;
 import com.willfp.eco.util.plugin.AbstractEcoPlugin;
 import org.bukkit.Bukkit;
 import org.bukkit.scheduler.BukkitTask;
@@ -22,44 +21,44 @@ public class EcoScheduler extends PluginDependent implements Scheduler {
     /**
      * Run the task after a specified tick delay.
      *
-     * @param callable   The lambda to run.
+     * @param runnable   The lambda to run.
      * @param ticksLater The amount of ticks to wait before execution.
      * @return The created {@link BukkitTask}.
      */
     @Override
-    public BukkitTask runLater(@NotNull final Callable callable,
+    public BukkitTask runLater(@NotNull final Runnable runnable,
                                final long ticksLater) {
-        return Bukkit.getScheduler().runTaskLater(this.getPlugin(), callable::call, ticksLater);
+        return Bukkit.getScheduler().runTaskLater(this.getPlugin(), runnable, ticksLater);
     }
 
     /**
      * Run the task repeatedly on a timer.
      *
-     * @param callable The lambda to run.
+     * @param runnable The lambda to run.
      * @param delay    The amount of ticks to wait before the first execution.
      * @param repeat   The amount of ticks to wait between executions.
      * @return The created {@link BukkitTask}.
      */
     @Override
-    public BukkitTask runTimer(@NotNull final Callable callable,
+    public BukkitTask runTimer(@NotNull final Runnable runnable,
                                final long delay,
                                final long repeat) {
-        return Bukkit.getScheduler().runTaskTimer(this.getPlugin(), callable::call, delay, repeat);
+        return Bukkit.getScheduler().runTaskTimer(this.getPlugin(), runnable, delay, repeat);
     }
 
     /**
      * Run the task repeatedly and asynchronously on a timer.
      *
-     * @param callable The lambda to run.
+     * @param runnable The lambda to run.
      * @param delay    The amount of ticks to wait before the first execution.
      * @param repeat   The amount of ticks to wait between executions.
      * @return The created {@link BukkitTask}.
      */
     @Override
-    public BukkitTask runAsyncTimer(@NotNull final Callable callable,
+    public BukkitTask runAsyncTimer(@NotNull final Runnable runnable,
                                     final long delay,
                                     final long repeat) {
-        return Bukkit.getScheduler().runTaskTimerAsynchronously(this.getPlugin(), callable::call, delay, repeat);
+        return Bukkit.getScheduler().runTaskTimerAsynchronously(this.getPlugin(), runnable, delay, repeat);
     }
 
     /**
@@ -76,12 +75,12 @@ public class EcoScheduler extends PluginDependent implements Scheduler {
     /**
      * Run the task asynchronously.
      *
-     * @param callable The lambda to run.
+     * @param runnable The lambda to run.
      * @return The created {@link BukkitTask}.
      */
     @Override
-    public BukkitTask runAsync(@NotNull final Callable callable) {
-        return Bukkit.getScheduler().runTaskAsynchronously(this.getPlugin(), callable::call);
+    public BukkitTask runAsync(@NotNull final Runnable runnable) {
+        return Bukkit.getScheduler().runTaskAsynchronously(this.getPlugin(), runnable);
     }
 
     /**
diff --git a/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/RunnableFactory.java b/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/RunnableFactory.java
index d128fea3..1004dbda 100644
--- a/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/RunnableFactory.java
+++ b/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/RunnableFactory.java
@@ -1,10 +1,11 @@
 package com.willfp.eco.util.bukkit.scheduling;
 
 import com.willfp.eco.util.factory.PluginDependentFactory;
-import com.willfp.eco.util.lambda.InputCallable;
 import com.willfp.eco.util.plugin.AbstractEcoPlugin;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.function.Consumer;
+
 public class RunnableFactory extends PluginDependentFactory {
     /**
      * Factory class to produce {@link EcoBukkitRunnable}s associated with an {@link AbstractEcoPlugin}.
@@ -18,14 +19,14 @@ public class RunnableFactory extends PluginDependentFactory {
     /**
      * Create an {@link EcoBukkitRunnable}.
      *
-     * @param callable Lambda of the code to run, where the parameter represents the instance of the runnable.
+     * @param consumer Lambda of the code to run, where the parameter represents the instance of the runnable.
      * @return The created {@link EcoBukkitRunnable}.
      */
-    public EcoBukkitRunnable create(@NotNull final InputCallable<EcoBukkitRunnable> callable) {
+    public EcoBukkitRunnable create(@NotNull final Consumer<EcoBukkitRunnable> consumer) {
         return new EcoBukkitRunnable(this.getPlugin()) {
             @Override
             public void run() {
-                callable.call(this);
+                consumer.accept(this);
             }
         };
     }
diff --git a/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/Scheduler.java b/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/Scheduler.java
index 03fe68af..ae597b3c 100644
--- a/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/Scheduler.java
+++ b/eco-util/src/main/java/com/willfp/eco/util/bukkit/scheduling/Scheduler.java
@@ -1,6 +1,5 @@
 package com.willfp.eco.util.bukkit.scheduling;
 
-import com.willfp.eco.util.lambda.Callable;
 import com.willfp.eco.util.plugin.AbstractEcoPlugin;
 import org.bukkit.scheduler.BukkitTask;
 import org.jetbrains.annotations.NotNull;
@@ -9,31 +8,31 @@ public interface Scheduler {
     /**
      * Run the task after a specified tick delay.
      *
-     * @param callable   The lambda to run.
+     * @param runnable   The lambda to run.
      * @param ticksLater The amount of ticks to wait before execution.
      * @return The created {@link BukkitTask}.
      */
-    BukkitTask runLater(@NotNull Callable callable, long ticksLater);
+    BukkitTask runLater(@NotNull Runnable runnable, long ticksLater);
 
     /**
      * Run the task repeatedly on a timer.
      *
-     * @param callable The lambda to run.
+     * @param runnable The lambda to run.
      * @param delay    The amount of ticks to wait before the first execution.
      * @param repeat   The amount of ticks to wait between executions.
      * @return The created {@link BukkitTask}.
      */
-    BukkitTask runTimer(@NotNull Callable callable, long delay, long repeat);
+    BukkitTask runTimer(@NotNull Runnable runnable, long delay, long repeat);
 
     /**
      * Run the task repeatedly and asynchronously on a timer.
      *
-     * @param callable The lambda to run.
+     * @param runnable The lambda to run.
      * @param delay    The amount of ticks to wait before the first execution.
      * @param repeat   The amount of ticks to wait between executions.
      * @return The created {@link BukkitTask}.
      */
-    BukkitTask runAsyncTimer(@NotNull Callable callable, long delay, long repeat);
+    BukkitTask runAsyncTimer(@NotNull Runnable runnable, long delay, long repeat);
 
     /**
      * Run the task.
@@ -46,10 +45,10 @@ public interface Scheduler {
     /**
      * Run the task asynchronously.
      *
-     * @param callable The lambda to run.
+     * @param runnable The lambda to run.
      * @return The created {@link BukkitTask}.
      */
-    BukkitTask runAsync(@NotNull Callable callable);
+    BukkitTask runAsync(@NotNull Runnable runnable);
 
     /**
      * Schedule the task to be ran repeatedly on a timer.
diff --git a/eco-util/src/main/java/com/willfp/eco/util/drops/telekinesis/EcoTelekinesisTests.java b/eco-util/src/main/java/com/willfp/eco/util/drops/telekinesis/EcoTelekinesisTests.java
index ac283cbf..bf20ed47 100644
--- a/eco-util/src/main/java/com/willfp/eco/util/drops/telekinesis/EcoTelekinesisTests.java
+++ b/eco-util/src/main/java/com/willfp/eco/util/drops/telekinesis/EcoTelekinesisTests.java
@@ -1,17 +1,17 @@
 package com.willfp.eco.util.drops.telekinesis;
 
-import com.willfp.eco.util.lambda.ObjectInputCallable;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.HashSet;
 import java.util.Set;
+import java.util.function.Function;
 
 public class EcoTelekinesisTests implements TelekinesisTests {
     /**
      * Set of tests that return if the player is telekinetic.
      */
-    private final Set<ObjectInputCallable<Boolean, Player>> tests = new HashSet<>();
+    private final Set<Function<Player, Boolean>> tests = new HashSet<>();
 
     /**
      * Register a new test to check against.
@@ -19,7 +19,7 @@ public class EcoTelekinesisTests implements TelekinesisTests {
      * @param test The test to register, where the boolean output is if the player is telekinetic.
      */
     @Override
-    public void registerTest(@NotNull final ObjectInputCallable<Boolean, Player> test) {
+    public void registerTest(@NotNull final Function<Player, Boolean> test) {
         tests.add(test);
     }
 
@@ -33,8 +33,8 @@ public class EcoTelekinesisTests implements TelekinesisTests {
      */
     @Override
     public boolean testPlayer(@NotNull final Player player) {
-        for (ObjectInputCallable<Boolean, Player> test : tests) {
-            if (test.call(player)) {
+        for (Function<Player, Boolean> test : tests) {
+            if (test.apply(player)) {
                 return true;
             }
         }
diff --git a/eco-util/src/main/java/com/willfp/eco/util/drops/telekinesis/TelekinesisTests.java b/eco-util/src/main/java/com/willfp/eco/util/drops/telekinesis/TelekinesisTests.java
index ad5ab5d0..b5c58475 100644
--- a/eco-util/src/main/java/com/willfp/eco/util/drops/telekinesis/TelekinesisTests.java
+++ b/eco-util/src/main/java/com/willfp/eco/util/drops/telekinesis/TelekinesisTests.java
@@ -1,16 +1,17 @@
 package com.willfp.eco.util.drops.telekinesis;
 
-import com.willfp.eco.util.lambda.ObjectInputCallable;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.function.Function;
+
 public interface TelekinesisTests {
     /**
      * Register a new test to check against.
      *
      * @param test The test to register, where the boolean output is if the player is telekinetic.
      */
-    void registerTest(@NotNull ObjectInputCallable<Boolean, Player> test);
+    void registerTest(@NotNull Function<Player, Boolean> test);
 
     /**
      * Test the player for telekinesis.
diff --git a/eco-util/src/main/java/com/willfp/eco/util/integrations/IntegrationLoader.java b/eco-util/src/main/java/com/willfp/eco/util/integrations/IntegrationLoader.java
index 3c4d5177..2b86a549 100644
--- a/eco-util/src/main/java/com/willfp/eco/util/integrations/IntegrationLoader.java
+++ b/eco-util/src/main/java/com/willfp/eco/util/integrations/IntegrationLoader.java
@@ -1,6 +1,5 @@
 package com.willfp.eco.util.integrations;
 
-import com.willfp.eco.util.lambda.Callable;
 import lombok.Getter;
 import org.jetbrains.annotations.NotNull;
 
@@ -8,7 +7,7 @@ public class IntegrationLoader {
     /**
      * The lambda to be ran if the plugin is present.
      */
-    private final Callable callable;
+    private final Runnable runnable;
 
     /**
      * The plugin to require to load the integration.
@@ -23,8 +22,8 @@ public class IntegrationLoader {
      * @param onLoad     The lambda to be ran if the plugin is present.
      */
     public IntegrationLoader(@NotNull final String pluginName,
-                             @NotNull final Callable onLoad) {
-        this.callable = onLoad;
+                             @NotNull final Runnable onLoad) {
+        this.runnable = onLoad;
         this.pluginName = pluginName;
     }
 
@@ -32,6 +31,6 @@ public class IntegrationLoader {
      * Load the integration.
      */
     public void load() {
-        callable.call();
+        runnable.run();
     }
 }
diff --git a/eco-util/src/main/java/com/willfp/eco/util/integrations/placeholder/PlaceholderEntry.java b/eco-util/src/main/java/com/willfp/eco/util/integrations/placeholder/PlaceholderEntry.java
index 305d2b89..041adc02 100644
--- a/eco-util/src/main/java/com/willfp/eco/util/integrations/placeholder/PlaceholderEntry.java
+++ b/eco-util/src/main/java/com/willfp/eco/util/integrations/placeholder/PlaceholderEntry.java
@@ -1,12 +1,13 @@
 package com.willfp.eco.util.integrations.placeholder;
 
-import com.willfp.eco.util.lambda.ObjectInputCallable;
 import lombok.Getter;
 import org.apache.commons.lang.Validate;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.function.Function;
+
 public class PlaceholderEntry {
     /**
      * The name of the placeholder, used in lookups.
@@ -17,7 +18,7 @@ public class PlaceholderEntry {
     /**
      * The lambda to retrieve the output of the placeholder given a player.
      */
-    private final ObjectInputCallable<String, Player> function;
+    private final Function<Player, String> function;
 
     /**
      * If the placeholder requires a player to lookup.
@@ -31,7 +32,7 @@ public class PlaceholderEntry {
      * @param function   A lambda to get the result of the placeholder given a player.
      */
     public PlaceholderEntry(@NotNull final String identifier,
-                            @NotNull final ObjectInputCallable<String, Player> function) {
+                            @NotNull final Function<Player, String> function) {
         this(identifier, function, false);
     }
 
@@ -43,7 +44,7 @@ public class PlaceholderEntry {
      * @param requiresPlayer If the placeholder requires a player.
      */
     public PlaceholderEntry(@NotNull final String identifier,
-                            @NotNull final ObjectInputCallable<String, Player> function,
+                            @NotNull final Function<Player, String> function,
                             final boolean requiresPlayer) {
         this.identifier = identifier;
         this.function = function;
@@ -60,7 +61,7 @@ public class PlaceholderEntry {
         if (player == null) {
             Validate.isTrue(!requiresPlayer, "null player passed to requiresPlayer placeholder.");
         }
-        return this.function.call(player);
+        return this.function.apply(player);
     }
 
     /**
diff --git a/eco-util/src/main/java/com/willfp/eco/util/lambda/Callable.java b/eco-util/src/main/java/com/willfp/eco/util/lambda/Callable.java
deleted file mode 100644
index e7fbdec3..00000000
--- a/eco-util/src/main/java/com/willfp/eco/util/lambda/Callable.java
+++ /dev/null
@@ -1,12 +0,0 @@
-package com.willfp.eco.util.lambda;
-
-/**
- * Represents code that can be later executed.
- */
-@FunctionalInterface
-public interface Callable {
-    /**
-     * Execute the lambda.
-     */
-    void call();
-}
diff --git a/eco-util/src/main/java/com/willfp/eco/util/lambda/InputCallable.java b/eco-util/src/main/java/com/willfp/eco/util/lambda/InputCallable.java
deleted file mode 100644
index 3e55bbf6..00000000
--- a/eco-util/src/main/java/com/willfp/eco/util/lambda/InputCallable.java
+++ /dev/null
@@ -1,16 +0,0 @@
-package com.willfp.eco.util.lambda;
-
-/**
- * Functional Interface that requires an object as a parameter.
- *
- * @param <A> The type of the object to require.
- */
-@FunctionalInterface
-public interface InputCallable<A> {
-    /**
-     * Execute the lambda.
-     *
-     * @param object The lambda parameter.
-     */
-    void call(A object);
-}
diff --git a/eco-util/src/main/java/com/willfp/eco/util/lambda/ObjectCallable.java b/eco-util/src/main/java/com/willfp/eco/util/lambda/ObjectCallable.java
deleted file mode 100644
index 1599a872..00000000
--- a/eco-util/src/main/java/com/willfp/eco/util/lambda/ObjectCallable.java
+++ /dev/null
@@ -1,16 +0,0 @@
-package com.willfp.eco.util.lambda;
-
-/**
- * Functional Interface to return a value of a given type.
- *
- * @param <A> The type to return.
- */
-@FunctionalInterface
-public interface ObjectCallable<A> {
-    /**
-     * Execute the lambda.
-     *
-     * @return The return value of the specified type.
-     */
-    A call();
-}
diff --git a/eco-util/src/main/java/com/willfp/eco/util/lambda/ObjectInputCallable.java b/eco-util/src/main/java/com/willfp/eco/util/lambda/ObjectInputCallable.java
deleted file mode 100644
index 674c981e..00000000
--- a/eco-util/src/main/java/com/willfp/eco/util/lambda/ObjectInputCallable.java
+++ /dev/null
@@ -1,18 +0,0 @@
-package com.willfp.eco.util.lambda;
-
-/**
- * Functional Interface to return a value of a specified type given a certain parameter.
- *
- * @param <A> The type of object to return
- * @param <B> The type of object for the parameter
- */
-@FunctionalInterface
-public interface ObjectInputCallable<A, B> {
-    /**
-     * Execute the lambda.
-     *
-     * @param object The lambda parameter.
-     * @return The required return type.
-     */
-    A call(B object);
-}
diff --git a/eco-util/src/main/java/com/willfp/eco/util/optional/Prerequisite.java b/eco-util/src/main/java/com/willfp/eco/util/optional/Prerequisite.java
index fe581904..8b7bc6da 100644
--- a/eco-util/src/main/java/com/willfp/eco/util/optional/Prerequisite.java
+++ b/eco-util/src/main/java/com/willfp/eco/util/optional/Prerequisite.java
@@ -1,7 +1,6 @@
 package com.willfp.eco.util.optional;
 
 import com.willfp.eco.util.ClassUtils;
-import com.willfp.eco.util.lambda.ObjectCallable;
 import lombok.Getter;
 import org.bukkit.Bukkit;
 import org.jetbrains.annotations.NotNull;
@@ -9,6 +8,7 @@ import org.jetbrains.annotations.NotNull;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.function.Supplier;
 
 public class Prerequisite {
     /**
@@ -41,7 +41,7 @@ public class Prerequisite {
     /**
      * Retrieve if the necessary prerequisite condition is met.
      */
-    private final ObjectCallable<Boolean> isMetCallable;
+    private final Supplier<Boolean> isMetSupplier;
 
     /**
      * The description of the requirements of the prerequisite.
@@ -52,22 +52,22 @@ public class Prerequisite {
     /**
      * Create a prerequisite.
      *
-     * @param isMetCallable An {@link ObjectCallable<Boolean>} that returns if the prerequisite is met
+     * @param isMetSupplier An {@link Supplier<Boolean>} that returns if the prerequisite is met
      * @param description   The description of the prerequisite, shown to the user if it isn't
      */
-    public Prerequisite(@NotNull final ObjectCallable<Boolean> isMetCallable,
+    public Prerequisite(@NotNull final Supplier<Boolean> isMetSupplier,
                         @NotNull final String description) {
-        this.isMetCallable = isMetCallable;
-        this.isMet = isMetCallable.call();
+        this.isMetSupplier = isMetSupplier;
+        this.isMet = isMetSupplier.get();
         this.description = description;
         VALUES.add(this);
     }
 
     /**
-     * Refresh the condition set in the callable, updates {@link this#isMet}.
+     * Refresh the condition set in the supplier, updates {@link this#isMet}.
      */
     private void refresh() {
-        this.isMet = this.isMetCallable.call();
+        this.isMet = this.isMetSupplier.get();
     }
 
     /**