From 1fc1ac6b2bca89c4595abfbe9960aec375e7ebd1 Mon Sep 17 00:00:00 2001
From: crc <crc@noemail.net>
Date: Thu, 2 Dec 2021 16:46:43 +0000
Subject: [PATCH] advent of code, day 2

FossilOrigin-Name: 9eb8ac12ee6e66bbb29ee03c38002a36a993e9f4f674919a572b1e7baadba2ca
---
 RELEASE-NOTES                           |  6 ++++
 example/advent-of-code-2021-day-2.retro | 42 +++++++++++++++++++++++++
 example/select.retro                    | 11 +++++++
 3 files changed, 59 insertions(+)
 create mode 100644 example/advent-of-code-2021-day-2.retro
 create mode 100644 example/select.retro

diff --git a/RELEASE-NOTES b/RELEASE-NOTES
index ca1a24d..b1d22c5 100644
--- a/RELEASE-NOTES
+++ b/RELEASE-NOTES
@@ -16,4 +16,10 @@
 
 # Documentation
 
+
 # Other
+
+# Examples
+
+- advent of code, 2021 (day 1, 2)
+- select.retro
diff --git a/example/advent-of-code-2021-day-2.retro b/example/advent-of-code-2021-day-2.retro
new file mode 100644
index 0000000..8a5cc3e
--- /dev/null
+++ b/example/advent-of-code-2021-day-2.retro
@@ -0,0 +1,42 @@
+As with day 1, the first part of this is easy. I'm "parsing"
+the input data by using `s:tokenize` and then unpacking the
+two element array. Convert the numeric part to a number, then
+a simple set of `s:case`s to process things.
+
+~~~
+:a:unpack [ ] a:for-each ;
+:parse    ASCII:SPACE s:tokenize a:unpack s:to-number swap ;
+
+:process
+  parse
+  'forward [ + ] s:case
+  'down    [ swap [ + ] dip ] s:case
+  'up      [ swap [ - ] dip ] s:case
+  drop-pair ;
+
+(depth,horizontal)
+#0 #0 'day2.input [ process ] file:for-each-line
+* n:put nl
+~~~
+
+The second half is modestly more difficult. As I'm minimizing
+any use of variables, this is a little messier than I'd prefer,
+but it's still pretty straightforward.
+
+I'm reusing the "parsing" part from the first half.
+
+My stack values are:  aim depth horizontal
+
+~~~
+:process
+  parse
+  'forward [ [ + ] [ 'abcd 'acbda reorder * + swap ] bi ] s:case
+  'down    [ [ rot ] dip + rot rot ] s:case
+  'up      [ [ rot ] dip - rot rot ] s:case
+  drop-pair ;
+
+(aim,depth,horizontal)
+#0 #0 #0 'day2.input [ process ] file:for-each-line
+
+* n:put nl drop (discard_the_aim_field)
+~~~
diff --git a/example/select.retro b/example/select.retro
new file mode 100644
index 0000000..98b490b
--- /dev/null
+++ b/example/select.retro
@@ -0,0 +1,11 @@
+Select will discard one of two values based on a passed
+flag.
+
+~~~
+:select (abf-) &drop &nip choose ;
+~~~
+
+```
+#100 #200 TRUE select n:put nl
+#100 #200 FALSE select n:put nl
+```