first commit
add the grammar chapter.
grammar and monad
add the monad chapter

Signed-off-by: Lorenz <laozhen.s@gmail.com>
add chapter layouts
add dynamic typing and weak typing subsection
add monad
more monad and introduction part
Signed-off-by: Lorenz <laozhen.s@gmail.com>
add grammar_ebnf files;
add syntax diagram
generic expression
list and if for while block explanation
monad transformers

Signed-off-by: Lorenz <laozhen.s@gmail.com>
more picture and the architecutre section.
new chapter
do notation
parse tree
statement evaluator
more sections
summary