From 93f984bd96baf641565f59620e6abe0eaee1c9d1 Mon Sep 17 00:00:00 2001
From: Krzosa Karol <krzosa.karol@gmail.com>
Date: Thu, 28 Jul 2022 14:04:33 +0200
Subject: [PATCH] Order independent declaration example

---
 examples/arrays_and_slices.kl              |  9 ++-
 examples/order_independent_declarations.kl | 73 ++++++++++++++++++++++
 main.cpp                                   |  2 +-
 3 files changed, 80 insertions(+), 4 deletions(-)
 create mode 100644 examples/order_independent_declarations.kl

diff --git a/examples/arrays_and_slices.kl b/examples/arrays_and_slices.kl
index 0a3a99a..ce42f1e 100644
--- a/examples/arrays_and_slices.kl
+++ b/examples/arrays_and_slices.kl
@@ -44,7 +44,10 @@ main :: (): int
 
   // After we loop and reassign slice values
   // old static_array gets changed
-  for slice
-    *it = 2
-  
+  //
+  // In this example, operator ';;' is used
+  // it inserts a new line, allows to write this
+  // example in a single line
+  for slice;; *it = 2
+
   assert(static_array[2] == 2)
\ No newline at end of file
diff --git a/examples/order_independent_declarations.kl b/examples/order_independent_declarations.kl
new file mode 100644
index 0000000..432cdcd
--- /dev/null
+++ b/examples/order_independent_declarations.kl
@@ -0,0 +1,73 @@
+/*
+Biggest problems with C/C++ are the header files and the fact that
+top level declarations are required to be ordered.
+
+In C++ you simply cannot write code like this:
+
+struct Asset{
+  Asset_Tag asset_tag;
+};
+
+enum Asset_Tag{
+  ASSET_SOUND,
+  ASSET_IMAGE,
+};
+
+Even though it makes more sense to do that, I would rather first learn
+about what Asset is rather then what tags it can have. C/C++ force on you
+an order of declarations that doesn't match what you have in your head.
+
+The next problem are the header files. Frequently on top of writing code,
+in C/C++ there is a need to maintain a header file. Header files contain
+all the forward declarations of the functions that you are implementing.
+Problem with this is that if you are changing something, potentially
+you now need to change that in multiple places. It would be nice if I could
+write a module that doesn't yet have any concrete spec but the functions
+are available everywhere, immediately. On top of that those functions would
+be nicely localized in a single file without thinking about what depends
+on what, how to fit it in the stack of includes etc. It would be just nice
+to tell the compiler to solve all those issues for us.
+*/
+
+// We can have main at the top level, this is something
+// that is sometimes pretty tricky in C++
+main :: (): int
+  // Even though Asset is beneath main, this still works
+  // this feature is even nicer when we think about modules etc.
+  asset1 := make_sound()
+  asset2 := make_sound()
+  asset1.next_asset = &asset2
+
+  // @todo: This does not work
+  // asset := []Asset{make_sound(), make_sound()}
+  // asset[0].next_sound = &asset[1]
+
+
+// Recursion is a pain point for this kinds of algorithms
+// As can be seen here it works very nicely
+make_sound :: (should_exit_recursion: Bool = false): Asset
+  if should_exit_recursion == true
+    asset: Asset
+    asset.tag = Asset_Tag.Sound
+    return asset
+  return make_sound(true)
+
+Asset :: struct
+  tag: Asset_Tag
+
+  // Pointers to self work as expected
+  // this is always a pain point for these kinds of
+  // algorithms
+  next_asset: *Asset
+
+// enum #flag assigns default values differently from normal enums.
+// It assigns a unique bit of a value to each enumeration.
+// Default values go: 1, 2, 4, 8, 16, 32, 64
+Asset_Tag :: enum #flag
+  Sound
+  Image
+  Text
+
+
+
+
diff --git a/main.cpp b/main.cpp
index 1d139bc..575341b 100644
--- a/main.cpp
+++ b/main.cpp
@@ -225,7 +225,7 @@ int main(int argument_count, char **arguments){
 
   Scratch scratch;
   Array<OS_File_Info> examples = os_list_dir(scratch, "examples"_s);
-  compile_file("examples/arrays_and_slices.kl"_s, COMPILE_AND_RUN);
+  compile_file("examples/order_independent_declarations.kl"_s, COMPILE_AND_RUN);
   // For(examples){
   //   if(it.is_directory) continue;
   //   compile_file(it.absolute_path, COMPILE_AND_RUN);