From 5cd71544b876818db2db58f7fb0344995aa33669 Mon Sep 17 00:00:00 2001
From: Robert Douglas <rwdougla@gmail.com>
Date: Tue, 5 Dec 2023 13:52:05 -0600
Subject: [PATCH] WIP

---
 sources/modules/functions/lambdas.md | 78 ++++++++++++++++++++++++----
 1 file changed, 67 insertions(+), 11 deletions(-)

diff --git a/sources/modules/functions/lambdas.md b/sources/modules/functions/lambdas.md
index d74b1aa..9516b8e 100644
--- a/sources/modules/functions/lambdas.md
+++ b/sources/modules/functions/lambdas.md
@@ -54,11 +54,13 @@ _Max 5 items._
 
 A student should be able to:
 
-1. Use a lambda taking a concrete type as a parameter and return a value in response
-2. 
-3. 
-4. 
-5. 
+1. Use a lambda taking a concrete type as a parameter and return a value
+2. transform a function definition into a lambda and use it
+3. enumerate trade-offs of code-locality using lambdas vs code reuse with free-functions
+4. assign a lambda to a variable for multiple calls
+5. named lambdas to increase code readability
+
+
 
 #### Caveats
 
@@ -79,14 +81,62 @@ _This section lists important details for each point._
 
 A student should be able to:
 
-1. Utilize std::function as a means to hold and transfer lambdas
+1. Utilize `std::function` as a means to hold and transfer lambdas
 2. Define a function-template taking a lambda as a template parameter
-3. Use captures to change
+3. specify, per parameter, whether to capture by reference or value
+4. specify the default capture type for a lambda
+5. use a lambda in a class, capturing and utilizing class data via `this`
+
+#### Caveats
+
+#### Points to cover
+
+motivation: 
+1. how to write library code to call user code? --- callbacks
+2. root finding using lambdas
+3. "customizing" generic algorithms
+
+### Advanced
+Explain why they can't write out the type of a lambda?
+_These are important topics that are not expected to be covered but provide
+guidance where one can continue to investigate this topic in more depth._
+
+
+#### Background/Required Knowledge
+
+* All of the above.
 
+#### Student outcomes
+
+A student should be able to:
+
+1. Use a lambda to introduce a new identifier for use within the body of the lambda
+2. explain the relationships between generic lambdas and templates
+3. construct an object with choice between 2 identifiers, using immediately-dispathced lambda
+4. utilize an immediately dispatched lambda to encode multiple statements where the language requires an expression
+5. use the `mutable` keyword to allow changing a captured-by-value or lambda-local value within the lambda body
+6. explicitly specify the return type for a lambda
+7. explain under what conditions an explicit return type is necessary
+ 
 #### Caveats
 
 #### Points to cover
 
+Construct an object with choice between 2 identifiers:
+```
+class X;
+bool b;
+X x = [c = b](){ if (c) return X(5, 10) else X("a", "b"); }();
+```
+
+multiple statements in a single expression
+```
+assert([](){
+	std::vector v{1, 2, 3, 4, 5};
+	for (auto x: v) std::cout << v << std::endl;
+}());
+```
+
 Capture can introduce new names
 ```
 char const* const s = "5";
@@ -96,6 +146,9 @@ char const* const s = "5";
 ```
 std::ranges::for_each(
 	std::vector{1,2,3,4,5},
+	// introducing new identifier
+	// generic lambda
+	// mutable allows changing "init"
 	[init = true] (auto&& x) mutable {
 		if (init) 
 		{ std::cout << x; init = false}; 
@@ -104,7 +157,10 @@ std::ranges::for_each(
 	});
 ```
 
-### Advanced
-Explain why they can't write out the type of a lambda?
-_These are important topics that are not expected to be covered but provide
-guidance where one can continue to investigate this topic in more depth._
+When to use lambdas or not:
+forcing code into a lambda can prevent some features
+```
+std::for_each(std::par_sec, v, [](){/* can't utilize OpenMP here */}};
+for(auto i : v){ /* OpenMP can be utilized here */ }
+```
+