From 8f5294fea7939524fdc4e21caa4ee71b9feab02e Mon Sep 17 00:00:00 2001
From: Stepan Usatiuk <stepan@usatiuk.com>
Date: Thu, 4 Jan 2024 12:41:19 +0100
Subject: [PATCH] even more docs

---
 README.md                 | 21 ++++++++++++++++++++-
 clitests/examples.psil    | 19 +++++++++++++++++++
 clitests/examples.psil.ex |  9 +++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 clitests/examples.psil
 create mode 100644 clitests/examples.psil.ex

diff --git a/README.md b/README.md
index dd949d7..fba11fb 100644
--- a/README.md
+++ b/README.md
@@ -87,4 +87,23 @@ Super debug mode:
 
 ```shell
 build/src/psil -f clitests/decorate.psil --repl- --command_strs+ --default_log_level:4 --log:MemoryContext:3
-```
\ No newline at end of file
+```
+
+# Some notes on the implementation
+
+The implementation is rather straightforward, based mostly on the compiler from "THE ARCHITECTURE OF SYMBOLIC
+COMPUTERS", with little modification and some additions. Notably, the let/letrec is more lisp-like, using racket-like
+name-value pairs instead of them being in separate lists like in the book. Also, there's support for top-level functions
+using `define`, and a simple concurrent garbage collector.
+
+There are three basic value types which is a string atom, number atom, and a cons cell.
+
+String atoms are basically used only internally, and you can't do much with them other than printing them. With number
+atoms you can do all the usual arithmetic, and they also serve as bools - any value greater than 0 is considered true
+for the purposes of `if`. And of course, all the usual stuff with cons cells - `car`, `cdr`, `cons`...
+
+Other language features were implemented to the extent that was required for writing some simple programs copied from
+what I have done for homework - it's in the `clitests` folder (and for simpler examples there's `examples.psil`, and it
+probably serves as the best reference for the
+language that this interpreter interprets :)
+
diff --git a/clitests/examples.psil b/clitests/examples.psil
new file mode 100644
index 0000000..23b12d0
--- /dev/null
+++ b/clitests/examples.psil
@@ -0,0 +1,19 @@
+(let ((plus (lambda (a b) (+ a b)))) (plus 2 3))
+(let ((minus (lambda (a b) (- a b)))) (minus 2 3))
+(let ((minusone (lambda (a b) (- a b))) (minustwo (lambda (a b) (- b a)))) (minustwo 2 (minusone 3 1)))
+
+(let ((iffn (lambda (a) (if a 1 2)))) (iffn 0))
+(let ((iffn (lambda (a) (if a 1 2)))) (iffn 1))
+(let ((iffn (lambda (a) (if (> a 1) 1 2)))) (iffn 1))
+(let ((iffn (lambda (a) (if (> a 1) 1 2)))) (iffn 2))
+
+(letrec ((fib (lambda (n)   (if (> n 0)
+                                (if (> n 1)
+                                    (+ (fib (- n 1))
+                                       (fib (- n 2)))
+                                    1)
+                                0))
+)) (fib 10))
+
+(define (globalplus x y) (+ x y))
+(globalplus 2 3)
\ No newline at end of file
diff --git a/clitests/examples.psil.ex b/clitests/examples.psil.ex
new file mode 100644
index 0000000..d0056cc
--- /dev/null
+++ b/clitests/examples.psil.ex
@@ -0,0 +1,9 @@
+5
+-1
+0
+2
+1
+2
+1
+55
+5
\ No newline at end of file