fixed bug and added a little documentation

samples/000_Overview.noja

@@ -0,0 +1,72 @@
+
+# ------------------------------------------------------------------------- #
+# --- Introduction -------------------------------------------------------- #
+#
+# 	This language was written as a personal study of how interpreters
+# and compilers work. For this reason, the language is very basic and 
+# not innovative.
+# 	One of the main inspirations was the CPython's source code since
+# it's extremely readable and has a very simple  clean architecture.
+#
+# 	This file was intended for people who already program in other 
+# high level languages (such as Python, Javascript, Ruby) and don't 
+# need to be introduced to basic programming concepts (variables, 
+# expressions and branches). This way, there is more space for the 
+# comparison of the language's features with the mainstream languages.
+#
+# ------------------------------------------------------------------------- #
+# --- Implementation ------------------------------------------------------ #
+#
+# The interpreter works by compiling the provided source to a bytecode 
+# format and executing it. The bytecode is very high level since it
+# does things like:
+#
+#	- explicitly referring to variables by name.
+#
+#	- treating values as atomic things: from the perspective of the 
+#	  bytecode, a list and an integer occupy the same space on the 
+#     stack, which is 1.
+# 
+# 	- referring to instructions by their index.
+#
+# For example, by compiling the following snippet
+
+define = true;
+
+if define:
+        a = 33;
+
+print(a, '\n');
+
+# one would obtain the following bytecode:
+#
+# 	 0: PUSHTRU 
+# 	 1: ASS 	[define] 
+# 	 2: POP 	1 
+# 	 3: PUSHVAR [define] 
+# 	 4: JUMPIFNOTANDPOP 8 
+# 	 5: PUSHINT 33 
+# 	 6: ASS 	[a] 
+# 	 7: POP 	1 
+# 	 8: PUSHSTR [\n]
+# 	 9: PUSHVAR [a] 
+# 	10: PUSHVAR [print] 
+# 	11: CALL 	2 
+# 	12: POP 	1 
+# 	13: RETURN
+#
+# as you can see, there are instructions like ASS and PUSHVAR that
+# assign to and read from variables by specifying names, and jumps
+# that refer to other points of the "executable" by specifying indices
+# (like JUMPIFNOTANDPOP) instead of raw addresses.
+#
+# 	All values (objects) are allocated on a garbage-collected heap. 
+# For this reason all variables are simply references to these objects.
+# The garbage collection algorithm is a copy-and-compact one. It 
+# behaves as a bump-pointer allocator until there is space left, 
+# and when space runs out, it creates a new heap, copies all of the 
+# alive object into it, calls the destructors of the dead objects 
+# and frees the old one.
+#
+# ------------------------------------------------------------------------- #
+# ------------------------------------------------------------------------- #