lambdas

Author: bowbahdoe

src/SUMMARY.md

@@ -15,12 +15,9 @@
     - [w3schools](./examples/w3schools.md)
     
 Project ideas:
-    calorie tracker
     tic tac toe
     chess
     go
-    CSV
-    image stuff with the PPM format
 
     swing game - maybe have a simplified game engine
 
@@ -37,7 +34,6 @@ airplane physics program
 ball throw physics program
 chemical stuff
 
-(after bytes) Make an audio file. Play hot cross buns.
 
 snake
 2048
@@ -66,7 +62,6 @@ HTML
 * Cursor Objects (sql)
 * Exception Hierarchies
 * Interior Iteration
-* Annotations
 
 Make your own iterator
 
@@ -88,13 +83,22 @@ Have a project that is just klarna but the your goal is "never write this progra
 - [Journal Entries]()
 
 sealed interfaces
+lambdas
 
 easy vs. simple
 
 enshittification state machine example (Acquire -> Make good for business bad for users -> Bad for everyone)
 
 Zombie Game
 
+try to trick someone into making that.
+LegBeanProviderFactory
+
+
+stuff in mooc i do not have 
+Streams
+Intro to testing
+Gui stuff
 -->
 
 # Modern Java
@@ -438,6 +442,12 @@ Zombie Game
   - [Inferred Types](./global_fields/inferred_types.md)
   - [Challenges](./global_fields/challenges.md)
 
+# Projects
+
+<!-- chicken nugget number type things come up when dispensing change -->
+- [Tic-Tac-Toe]()
+
+
 # Concepts
 
 - [Code is Read more than Written](./code_is_read_more_than_written.md)
@@ -735,7 +745,7 @@ Make them do one. -->
   - [Inferred Types](./loops_iii/inferred_types.md)
   - [Challenges](./loops_iii/challenges.md)
 
-# Concepts II
+# Concepts III
 
 - [Encapsulation](./encapsulation.md)
   - [Implementation Details](./encapsulation/implementation_details.md)
@@ -820,6 +830,13 @@ Make them do one. -->
   - [Final Classes](./class_extension/final_classes.md)
   - [Challenges](./class_extension/challenges.md)
 
+<!--
+# Concepts IV
+
+- [Easy vs. Simple]()
+- [Read the Docs]()
+-->
+
 
 # Data Types IX
 
@@ -849,6 +866,21 @@ Make them do one. -->
   - [Multi-Module Directory Layout](./modules/multi_module_directory_layout.md)
   - [Purpose](./modules/purpose.md)
   - [Challenges](./modules/challenges.md)
+
+- [Lambdas](./lambdas.md)
+  - [Functional Interfaces](./lambdas/functional_interfaces.md)
+  - [@FunctionalInterface](./lambdas/functional_interface_annotation.md)
+  - [Lambda Expressions](./lambdas/lambda_expressions.md)
+  - [Arguments](./lambdas/arguments.md)
+  - [Return](./lambdas/return.md)
+  - [Method References](./lambdas/method_references.md)
+  - [Inference](./lambdas/inference.md)
+  - [Built-In Functional Interfaces](./lambdas/built_in_functional_interfaces.md)
+  - [Runnable](./lambdas/runnable.md)
+  - [Function](./lambdas/function.md)
+  - [Checked Exceptions](./lambdas/checked_exceptions.md)
+  - [Challenges](./lambdas/challenges.md)
+
 <!--
 - [Lambdas](./lambdas.md)
   - [Functional Interfaces](./lambdas/functional_interfaces.md)
@@ -911,6 +943,51 @@ TODO: Wait for hermetic java
   - [javadoc](./documentation/javadoc.md)
   - [Challenges](./documentation/challenges.md)
 
+# Data Types X
+
+- [Streams 🚧](./streams.md)
+  - [Purpose](./streams/purpose.md)
+  - [stream](./streams/stream.md)
+  - [map](./streams/map.md)
+  - [filter](./streams/filter.md)
+  - [Collectors](./streams/collectors.md)
+  - [toList](./streams/toList.md)
+  - [Challenges](./streams/challenges.md)
+<!-- - [Regular Expressions 🚧]()
+- [Strings III 🚧]()
+
+
+# Code Structure IX
+
+- [Sealed Interfaces 🚧]()
+  - [permits]()
+  - [non-sealed]()
+  - [Reflection]()
+- [Generics II 🚧]()
+  - [Bounds]()
+  - [Wildcards]()
+  - [Invariance]()
+
+# Control Flow VI
+
+- [Switch IV 🚧]()
+  - [Patterns]()
+  - [when]()
+
+# Testing
+
+- [Manual Testing 🚧]()
+- [Logging 🚧]()
+
+# Concurrent Programs
+
+- [Threads 🚧]()
+  - [UncaughtExceptionHandler]()
+  - [Races]()
+
+# Concepts IV
+
+- []()  -->
 
 <!--- 
 PROJECT IDEAS:
@@ -925,9 +1002,6 @@ PROJECT IDEAS:
 
 
 
-[HashMap](./hash_map.md)
-
-
 
 # Code Structure V
 - [Interface Extension](./interface_extension.md)
@@ -938,12 +1012,6 @@ PROJECT IDEAS:
 
 # Building
 
-- [Compilation]()
-- [Compile Java Code]()
-  - [Compile a List of Files]()
-  - [Specify Where to Find Sources]()
-  - [Enable Debug Info]()
-- [Package Java Code]()
 - [Consume External Libraries]()
 
 # Data Types VI
@@ -982,11 +1050,6 @@ PROJECT IDEAS:
 
 
 
-# Concepts
-
-
-# Concepts
-
 
 - [The Idiot Game](./the_idiot_game.md)
 
@@ -1009,20 +1072,14 @@ PROJECT IDEAS:
 
 # Data Types VI
 
-- [Integers II]()
 - [Paths]()
 - [Exceptions II]()
 
 # Control Flow IV
 
 # Algorithms II
 
-# Data Types VII
 
-- [Maps]()
-  - [HashMap]()
-- [Sets]()
-  - [HashSet]()
 
 <!--
 
@@ -1046,27 +1103,20 @@ Maven
 XML
 Pom
 Multiversal Equality
-Reflection
-    Cover Invoking *public* constructs
-Javadoc and Documentation comments
 -->
 
 <!--
 # Legacy Java
 - [Legacy Java]()
     - [Prelude]()
     - [Subpar]()
-        - [Short]()
         - [Scanner]()
         - [File]()
         - [Swing]()
         - [Date]()
     - [Crusty]()
         - [Vector]()
         - [Hashtable]()
-    - [Already Removed]()
-        - [Applets]()
-        - [Finalization]()
 -->
 
 <!--

src/interfaces/challenges.md

@@ -84,3 +84,28 @@ interface Tarot {
     String standUser();
 }
 ```
+
+## Challenge 5.
+
+Make a method named `promptGeneric` which can prompt the user for information
+but, based on if what they typed is properly interpretable, can reprompt them.
+
+As part of this make a `Parser` interface and at least two implementations: `IntParser`
+and `DoubleParser`.
+
+```java
+// CODE HERE
+
+class Main {
+    // CODE HERE
+
+    void main() {
+        int x = promptGeneric(
+            "Give me an x: ", new IntParser()
+        );
+        double y = promptGeneric(
+            "Give me a floating point y: ", new DoubleParser()
+        );
+    }
+}
+```

src/lambdas.md

@@ -1,3 +1,37 @@
 # Lambdas
 
+<img src="/lambdas/header.png" height="200px"/>
 
+
+Making an implementation of `interface`s that
+only require one method turns out to be a common
+task for a Java developer.
+
+```java,no_run
+interface Band {
+    void playHitSong();
+}
+
+class Starcadian implements Bank {
+    @Override
+    public void playHitSong() {
+        IO.println("ultralove");
+    }
+}
+```
+
+As such there is a mechanism called "lambdas"
+which lowers the effort required to do so.
+
+```java
+interface Band {
+    void playHitSong();
+}
+
+class Main {
+    void main() {
+        Band starcadian = () -> IO.println("ultralove");
+        starcadian.playHitSong();
+    }
+}
+```

src/lambdas/Screenshot 2025-08-25 at 7.04.29 AM.png

@@ -0,0 +1,70 @@
+# Arguments
+
+If the method on the functional interface takes arguments
+you can include those in the parentheses before the `->`.
+
+```java
+@FunctionalInterface
+interface Singer {
+    void sing(String title, double volume);
+}
+
+class Main {
+    void main() {
+        Singer woodkid = (String title, double volume) -> {
+            IO.println(
+                title 
+                    + " by woodkid is now " 
+                    + (volume > 10 ? "BLASTING" : "playing"
+                )
+            );
+        };
+
+        // AC Revelations wasn't the best game
+        // but that trailer was awesome.
+        woodkid.sing("Iron", 11);
+    }
+}
+```
+
+If it won't lead to any ambiguity Java also allows you to omit the types
+from the argument list.
+
+```java
+@FunctionalInterface
+interface Singer {
+    void sing(String title, double volume);
+}
+
+class Main {
+    void main() {
+        Singer twrp = (title, volume) -> {
+            IO.println(
+                title 
+                    + " by twrp is now " 
+                    + (volume > 10 ? "BLASTING" : "playing"
+                )
+            );
+        };
+
+        woodkid.sing("Pets", 7);
+    }
+}
+```
+
+Further, if there is only one argument you may omit even the `()`.
+
+```java
+@FunctionalInterface
+interface Conductor {
+    void conduct(String tempo);
+}
+
+class Main {
+    void main() {
+        Conductor jkSimmons = tempo -> IO.println("Not my tempo.")
+
+        jkSimmons.conduct("4/4");
+    }
+}
+```