fixed bug and added a little documentation

samples/100_Expressions.noja

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+
+# ------------------------------------------------------------------------- #
+# --- The first program --------------------------------------------------- #
+#
+# The sintax is similar to Python's but is more C-like. A Noja script 
+# is a list of statements that can be:
+# 
+#   - function declaractions
+#	- expressions
+#	- if-else branches
+#	- while loops
+#	- do-while loops
+#	- return statements
+#	- composit statements
+#
+# The most basic yet interesting program is:
+
+print('Hello, world!\n'); 
+
+# as in other languages, this kind of statement is an expression.
+# Expression statements require a ';' to determine their end.
+#
+# The print function can take any number of arguments of any type
+# and doesn't add any spaces or newlines to the output. 
+
+print(1, 2, 3, '\n');
+
+# ------------------------------------------------------------------------- #
+# --- Variables and expressions ------------------------------------------- #
+# 
+# You can set variables without declaring them first by using the
+# assignment operator:
+
+a = 5;
+
+# which is similar to Python's assignment, but is a little different.
+# In this language, assignments are considered as expressions, in fact 
+# you can do things like
+
+a = (b = 1) + 1;
+
+# The value resulting from an assignment is the assigned value.
+# After this expression, b's value is 1 and a's value is 2. 
+
+print('b = ', b, '\n'); # b = 1
+print('a = ', a, '\n'); # a = 2
+
+# all of the basic arithmetic operators are available:
+
+x = 1 + 1;
+y = 1 - 2;
+z = 3 * 2;
+w = 10 / 3;
+
+print('x = ', x, '\n'); # x = 2
+print('y = ', y, '\n'); # y = -1
+print('z = ', z, '\n'); # z = 6
+print('w = ', w, '\n'); # w = 3
+
+# Note how the division returns the rounded down version of the result.
+# This is because the division was performed on integers. By making one
+# of the operands a floating point value, also a floating point result
+# is returned:
+
+w = 10 / 3.0;
+
+print('w = ', w, '\n'); 
+
+# Arithmetic operators are only available for numeric types of objects.
+# If you try to apply them on other kinds of types, you get a runtime
+# error:
+
+# (Uncomment the following line and run this file to get the error)
+# p = 5 + 'hello'; 
+
+# And relational operators are also available:
+
+print(1 < 2, '\n');  # true
+print(1 > 2, '\n');  # false
+
+print(1 >= 0, '\n'); # true
+print(1 <= 0, '\n'); # false
+
+print(1 == 5, '\n'); # false
+print(6 == 6, '\n'); # true
+
+print(1 != 5, '\n'); # true
+print(6 != 6, '\n'); # false
+
+# The equal and not equal operators are available on every type of object,
+# while the others are only available for numeric types.
+#
+# ------------------------------------------------------------------------- #
+# ------------------------------------------------------------------------- #