commit ebdf81a92608364c8e81a3ac21c4e7db873a1da4
Author: Martin Potier <martin.potier@relexsolutions.com>
Date:   Thu Jan 11 09:24:25 2018 +0200

    Initial commit

diff --git a/ep0001/Solution.md b/ep0001/Solution.md
new file mode 100644
index 0000000..8023d29
--- /dev/null
+++ b/ep0001/Solution.md
@@ -0,0 +1,163 @@
+# FPKATA #01: In the library…
+
+(Soundtrack: Arch Enemy — War Eternal)
+
+(Inspired from this exercice: http://www.codewars.com/kata/54dc6f5a224c26032800005c/train/haskell)
+
+## Introduction
+
+You are stuck in a library with a very talkative and experimental science-minded IA. It keeps repeating the following:
+
+> — Pleeease, can you help me?
+
+> — …
+
+> — Pleaaase, can you help?
+
+> — …
+
+> — Hellooooo?
+
+> — …
+
+Since you would really like to have peace, you dare ask:
+
+> — What's the matter?
+
+> — My code is incomplete, I've lost my code, please help!
+
+> — What code? What are you talking about?
+
+> — I really need to sort the library index and count how many books have the same first-letter reference, but only in from a list…
+
+> — Wait!
+
+> — … of characters that my master will provide.
+
+> This makes no sense, can't you write it down?
+
+A few seconds pass in total silence. Then, there's a sound coming from your right, something like an inkjet printer work at a fast pace. It's actually a printer. It throws the printed sheet of paper at you in a furious “TWEEEEEEEEEEEP”. You pick up the paper and read:
+
+    INPUT................:
+      LIBRARY COUNT......: [("ABOOK", 12), ("BPDEXU", 45), ("BJLDRSA", 15), ("CLDAVB", 98), ("DAJLDI", 32)]
+      INDICES............: ['A','B','C','W']
+    OUTPUT...............:
+      INDEX COUNT........: [('A',12),('B',60),('C',98),('W',0)]
+    TIME TO GOOD ANSWER..: 203 years
+
+You frown:
+
+> — It took you so long to find this?
+
+> — Can you help me? I've lost my code, my dedicated code for this task.
+
+> — Well, you managed to get this one right, didn't you?
+
+> — Nooooo! Master is going to unplug me if I use bruteforce again! Master was
+    very unhappy with my performance! I want to live! Please help me!
+
+> — Ok, all right, calmn down, there, there… What are programmed with?
+
+> — Elm.
+
+Of course it's Elm…
+
+## Outline
+
+```
+module Main exposing (..)
+
+import Html exposing (text)
+
+
+type Stock
+    = Stock String Int
+
+
+library1 : List Stock
+library1 =
+    [ Stock "ABART" 20
+    , Stock "CDXEF" 50
+    , Stock "BKWRK" 25
+    , Stock "BTSQZ" 89
+    , Stock "DRTYM" 60
+    ]
+
+
+categories1 : List Char
+categories1 =
+    [ 'A'
+    , 'B'
+    , 'C'
+    , 'W'
+    ]
+
+
+stockList : List Stock -> List Char -> List ( Char, Int )
+stockList st cs =
+    <THIS IS BLANK, FILL ME>
+
+
+main =
+    text (toString (stockList library1 categories1))
+```
+
+## Walkthrough
+
+Ok, so you'll have to fill the blank. After a few minutes, you identify two
+main components: one is about taking the first letter of every `Stock` name. The
+second is finding the amount of each `Char` in a `List (Char, Int)`.
+> 
+Let's start with the second point and assume we have a value of `List (Char,
+Int)` already available. We know at least to functions to recurse on lists:
+maps and folds. Clearly, we'll have to choose a fold, since some aggregating is
+needed when several identical `Char` are in the list. Let's pick foldl, it does
+not really matter right now. So, the type of `List.foldl` is:
+
+    foldl : (a -> b -> b) -> b -> List a -> b
+
+In fact, you notice you'll need two folds! One inner fold for counting of many
+book for initial X, and one outer fold for going through all the initials
+required by the master.
+
+### Inner foldl: how many books with Initial X
+
+You think about using type aliases to make your code easier to read, the IA
+won't mind. To specialize your inner foldl, which is morally a foldlForX, you
+identify `a` as an element of a library stock (even though the title has been
+shortened already to its initial), and `b` as the final index count.
+
+    type alias Initial = Char
+    type alias Count = Int
+    type alias TitleCount = (Initial, Int) 
+    type alias FinalCount = (Initial, Int)
+
+You rewrite your specialized foldl type signature to account for the type
+aliases:
+
+    foldForX : (TitleCount -> FinalCount -> FinalCount)
+          -> FinalCount
+          -> List TitleCount
+          -> FinalCount
+
+After a call to this, you'll get how many books have a title that starts with
+the initial X.
+
+You are missing the function with type `(TitleCount -> FinalCount ->
+FinalCount)`, and you reflect a little bit on its name and on its usage. Hmmm,
+it takes a TitleCount and a FinalCount and returns a (new) FinalCount? You
+choose to call it:
+
+    updateFinalCount : (TitleCount -> FinalCount -> FinalCount)
+
+Actually it takes another (hidden) parameter, you change its name to reflect
+that:
+
+    updateFinalCountForX : (TitleCount -> FinalCount -> FinalCount)
+    updateFinalCountForX t f =    
+
+
+NB:
+addBio : String -> User -> User
+addBio bio user =
+  { user | bio = bio }