diff --git a/README b/README
new file mode 100644
index 0000000000000000000000000000000000000000..6750fb09d7969a3670ad103b157a1371e5f7ac4f
--- /dev/null
+++ b/README
@@ -0,0 +1,64 @@
+* COMMENT -*- mode: org -*-
+#+Date: 2015-09-07
+Time-stamp: <2015-09-07>
+
+* 2015-09-07 write an apache2 access log parser in haskell.
+practice using attoparsec.
+
+10.21.176.7 - - [06/Sep/2015:06:26:02 +0800] "GET /v3/auth/tokens HTTP/1.1" 200 3997 "-" "-" 1011068
+10.21.176.7 - - [06/Sep/2015:06:26:03 +0800] "GET /v3/auth/tokens HTTP/1.1" 200 4065 "-" "python-requests/2.2.1 CPython/2.7.3 Linux/3.13.0-38-generic" 5481
+10.21.176.7 - - [06/Sep/2015:06:26:02 +0800] "GET /v2.0/tokens/e79ce79f16f04852a7d981009090fb75 HTTP/1.1" 200 2692 "-" "python-requests/2.2.1 CPython/2.7.3 Linux/3.13.0-40-generic" 879293
+10.21.176.7 - - [06/Sep/2015:06:50:02 +0800] "POST /v2.0/tokens HTTP/1.1" 200 2615 "-" "python-neutronclient" 211874238
+
+allow me to
+- filter slow requests.
+  -gt 2s
+
+- find most frequent request.
+  order by request verb and path frequency.
+  print out first N most frequently viewed verb&path.
+
+  get top 5 request
+  cd /var/log/apache2
+  ~sylecn/a2p -i access.keystone.admin.ssl.log -t 5
+
+  stack build && stack exec a2p -- -i ~/d/t1 --top 1
+
+  output for user:
+  M%   COUNT     POST xxx
+  M%   COUNT     GET xxx
+
+  return value for this
+  Map (verb, path) count
+  Order by count.
+  get first N.
+
+  filter the map before converting to alist.
+
+  - how to do insert or update? when doing counting.
+    you have to use lookup. it's probably not thread safe.
+
+  - works perfectly on production access log.
+
+how to use the parser?
+
+a2p -i ACCESS_LOG_FILE [-gt 20s]
+
+- created project at ~/haskell/apache2-log-parser
+
+- let's test parse efficiency first.
+  print a summary line:
+  parsed N input lines in M seconds. (P line/s)
+
+  - support -f param and parsing lines from file.
+
+  - can't convert duration to Int easily.
+
+- Applicative is powerful. I didn't know about <* before.
+  logParser :: Parser [AccessLog]
+  logParser = many $ parseLine <* endOfLine
+
+- how to use int type param in optparse-applicative?
+
+  haskell - How to use Int with the optparse-applicative inside a data constructor? - Stack Overflow
+  http://stackoverflow.com/questions/31636962/how-to-use-int-with-the-optparse-applicative-inside-a-data-constructor