diff --git a/README.md b/README.md
index ec47cc1..c028593 100644
--- a/README.md
+++ b/README.md
@@ -3,4 +3,159 @@ human-friendly-id-gen
 
 New Haskell project to generate Human Friendly Ids.
 
-Those ids should be easy to read, write and to remember.
+Those ids should be easier to read / write and remember than classical random
+base64 ids.
+
+The package provide both a lib and an executable `hfig` (for Human Friendly
+ Identifier Generator).
+
+## Strategies
+
+There are different strategies depending on your preferences.
+
+### Short strategy
+
+We generate random phonemes that should be not too hard to pronounce but in the
+same time having sufficiently different phonemes to be able to have not too long
+words to prevent collision.
+
+~~~
+rupomdovi
+waziridro
+moplaloxo
+kankujochplu
+drubrusadka
+dripuxmopbi
+jotchibluzuv
+plotabrprabudr
+zopranblokplab
+tirbrozprakow
+~~~
+
+Here is the probability of collision if you generate a sample of n of those words:
+
+| n    |      % |
+|------|--------|
+| 1000 | 2.5e-8 |
+| 10k  | 2.5e-6 |
+| 100k | 2.5e-4 |
+| 1M   | 2.5e-2 |
+
+You can also ask to use more phonemes if you only use 2 phonemes which generate words like:
+
+~~~
+blilwa
+wirpa
+winupl
+tani
+ludu
+probrip
+pichprox
+joprux
+drudibl
+zibrku
+~~~
+
+The probility of collision become:
+
+| n   |    % |
+|-----|------|
+| 10  | 1e-5 |
+| 100 | 1e-3 |
+| 1k  | 0.11 |
+| 10k |  1.0 |
+
+### Lovecraftian strategy
+
+My nickname isn't yogsototh for nothing so why not generate as if Lovecraft
+could have invented them.
+
+~~~
+ymhiovhotl
+zhaobritl
+v'odher
+neltha
+ucnouthlaxr
+kola
+adavhig
+ctuthrilbh
+yakthembru
+athoubr'murh
+~~~
+
+The probability collision table looks like:
+
+| n    |                    % |
+|------|----------------------|
+| 10   | 6.669334400426838e-8 |
+| 100  | 6.669334400426838e-6 |
+| 1k   | 6.669334400426837e-4 |
+| 10k  | 6.669334400426838e-2 |
+| 100k |                  1.0 |
+
+if you generate two names for an id, you should be safe.
+
+| n    |       % |
+|------|---------|
+| 10   | 8.8e-17 |
+| 100  | 8.8e-15 |
+| 1k   | 8.8e-13 |
+| 10k  | 8.8e-11 |
+| 100k |  8.8e-9 |
+| 1M   |  8.8e-7 |
+
+### Dictionary Strategy
+
+You can read any file and each line will be considered as a word.
+We then take a few random words.
+
+You can gather some word list in this repository to use.
+
+There is a default english dictionary with approximatively 370k English words.
+
+Here is an example:
+
+~~~
+shuckins-digitinerved-microspectrophotometrical
+indeterminableness-getaways-sceloporus
+diverts-okayed-cast
+semirhythmically-thasian-thrawart
+smashups-phototherapeutics-swollenness
+bindingness-phoenicia-ringy
+execs-axes-barotaxis
+monimiaceous-presutural-submembers
+heterodyned-pourparley-zecchino
+fragmentate-contrude-taeniae
+~~~
+
+And here are the different table of collision probability.
+
+use 1 word to make the identifier:
+
+|       n |      % |
+|---------|--------|
+|      10 | 1.3e-4 |
+|     100 | 1.3e-2 |
+|      1k |    1.0 |
+
+combine 2 words to make the identifier:
+
+| n    |       % |
+|------|---------|
+| 10   | 3.6e-10 |
+| 100  |  3.6e-8 |
+| 1k   |  3.6e-6 |
+| 10k  |  3.6e-4 |
+| 100k |  3.6e-2 |
+| 1M   |     1.0 |
+
+combine 3 words to make the identifier:
+
+| n    |       % |
+|------|---------|
+| 10   | 9.8e-16 |
+| 100  | 9.8e-14 |
+| 1k   | 9.8e-12 |
+| 10k  | 9.8e-10 |
+| 100k |  9.8e-8 |
+| 1M   |  9.8e-6 |
diff --git a/src-exe/Main.hs b/src-exe/Main.hs
index 67c32a2..2cfaf6d 100644
--- a/src-exe/Main.hs
+++ b/src-exe/Main.hs
@@ -17,13 +17,9 @@ main = do
     Short -> Short.idgen (fromMaybe 4 (optLen opts)) >>= putText
     Lovecraftian -> Lovecraftian.idgen (fromMaybe 1 (optLen opts)) >>= putText
     Dict  -> do
-      let file = case optDict opts of
-                   Just "english"     -> "dictionaries/english.txt"
-                   Just "first-names" -> "dictionaries/first-names.txt"
-                   Just "generic"     -> "dictionaries/generic.txt"
-                   Just "literary"    -> "dictionaries/literary.txt"
-                   Just filepath      -> toS (format fp filepath)
-                   Nothing            -> "dictionaries/english.txt"
+      file <- case optDict opts of
+                Just filepath      -> return $ toS (format fp filepath)
+                Nothing            -> die "Please select a dictionary file with the -d or --dict options"
       dict <- Dict.dictionaryFromFile file
       Dict.idgen dict (fromMaybe 3 (optLen opts)) >>= putText
 
diff --git a/src/HFIG/Dictionary.hs b/src/HFIG/Dictionary.hs
index d5339fb..ef652b7 100644
--- a/src/HFIG/Dictionary.hs
+++ b/src/HFIG/Dictionary.hs
@@ -13,58 +13,23 @@ Yet not the best for preventing collision.
 module HFIG.Dictionary
   ( idgen
   , dictionaryFromFile
-  , collisionProbability
   )
 where
 
 import Protolude
 
-import qualified System.Random.MWC as Random
-import qualified Control.Monad.Primitive as Prim
 import qualified Data.Vector as V
 import qualified Data.Text as T
 
+import qualified HFIG.Helpers as Helpers
+
 type Dictionary = V.Vector Text
 
+
 -- | Will generate readable short names The integer parameter determine the
 -- length in number of syllabus of the name
 idgen :: Dictionary -> Int -> IO Text
-idgen allwords n =
-  Random.withSystemRandom $ \gen ->
-    T.intercalate "-" <$> replicateM n (genWord gen allwords)
-
--- | Approximate collision probability other n generated name with complexity
--- parameter equal to l
---
--- For example if you generate 1000 words randomly with complexity parameter 4
--- We estimate the probability of collision to 3.85%
---
--- This is a nice helper function to use when you want to estimate the optimal
--- length of your ids
---
--- @
--- > collisionProbability 1000 4
--- 3.8580246913580245e-2
---
--- > collisionProbability 10000 5
--- 6.430041152263374e-2
---
--- > collisionProbability 10000 6
--- 1.0716735253772291e-3
--- @
-collisionProbability :: V.Vector Text -- ^ The dictionary
-                     -> Double -- ^ nb of generated names
-                     -> Double -- ^ length parameter used
-                     -> Double
-collisionProbability dict n l = min ((n**2) / (2 * (nbWords dict ** l))) 1
-
-nbWords :: V.Vector Text -> Double
-nbWords ws = fromIntegral $ V.length ws
-
-genWord :: Random.Gen (Prim.PrimState IO) -> V.Vector Text -> IO Text
-genWord gen allwords = do
-  (k :: Int) <- Random.uniformR (0, V.length allwords - 1) gen
-  return (allwords V.! k)
+idgen d = Helpers.idgen "-" [d]
 
 dictionaryFromFile :: FilePath -> IO (V.Vector Text)
 dictionaryFromFile dictName = (V.fromList . T.lines) <$> readFile dictName
diff --git a/src/HFIG/Lovecraftian.hs b/src/HFIG/Lovecraftian.hs
index 3f5fc1b..9f0cda6 100644
--- a/src/HFIG/Lovecraftian.hs
+++ b/src/HFIG/Lovecraftian.hs
@@ -12,7 +12,6 @@ Yet not the best for preventing collision.
 -}
 module HFIG.Lovecraftian
   ( idgen
-  , collisionProbability
   )
 where
 
@@ -43,16 +42,3 @@ nameparts = [
   , V.fromList ["a","e","i","u","o"]
   , V.fromList ["","","","","","","","","","","d","g","h","l","lb","lbh","n","r","rc","rh","s","sh","ss","st","sz","th","tl","x","xr","xz"]
   ]
-
--- | Approximate collision probability other n generated name with complexity
--- parameter equal to l
---
--- For example if you generate 1000 words randomly with complexity parameter 4
--- We estimate the probability of collision to 3.85%
---
--- This is a nice helper function to use when you want to estimate the optimal
--- length of your ids
-collisionProbability :: Double -- ^ nb of generated names
-                     -> Double -- ^ length parameter used
-                     -> Double
-collisionProbability = Helpers.collisionProbability nameparts