Update frontpage examples

Author: garazdawi

_examples/1-fact-large.md

@@ -0,0 +1,15 @@
+---
+description: Functional programming
+display: large
+---
+<!-- This file has to be 15 lines long -->
+```erlang
+fact(1) -> 1;              %% Pattern matching for control-flow
+fact(N) -> N * fact(N-1).  %% Recursion to create loops
+
+> example:fact(10).        %% Interactive shell for fast iterations
+3628800
+> [{I, example:fact(I)} || I <- lists:seq(1,10)].
+[{1, 1}, {2, 2}, {3, 6}, {4, 24}, {5, 120}, {6, 720},
+ {7, 5040}, {8, 40320}, {9, 362880}, {10, 3628800}]
+```

_examples/1-fact.md

@@ -0,0 +1,13 @@
+---
+description: Functional programming
+display: small
+---
+<!-- This file has to be 13 lines long -->
+```erlang
+%% Return factorial for N
+fact(1) -> 1;
+fact(N) -> N * fact(N-1).
+
+> example:fact(10).
+3628800
+```

_examples/2-fact-small.md

@@ -0,0 +1,15 @@
+---
+description: Higher-order functions
+display: large
+---
+<!-- This file has to be 15 lines long -->
+```erlang
+> Fruits = ["banana","monkey","jungle"].     %% Immutable variables
+["banana","monkey","jungle"]
+> lists:map(fun string:uppercase/1, Fruits). %% Map values using stdlib functions
+["BANANA","MONKEY","JUNGLE"]
+%% Fold over lists using custom functions
+> lists:fold(fun(Str, Cnt) -> string:length(Str) + Cnt end, 0, Fruits).
+17
+
+```

_examples/2-lists.md

@@ -0,0 +1,13 @@
+---
+description: Higher-order functions
+display: small
+---
+<!-- This file has to be 13 lines long -->
+```erlang
+> Fruits = ["banana","monkey"].
+["banana","monkey"]
+> lists:map(
+    fun string:uppercase/1,
+    Fruits).
+["BANANA","MONKEY"]
+```

_examples/3-lists-large.md

@@ -0,0 +1,15 @@
+---
+description: Light-weigth processes
+display: large
+---
+<!-- This file has to be 15 lines long -->
+```erlang
+> Parent = self().                         %% Get own process id
+<0.376.0>
+> Child = spawn(fun() -> receive go -> Parent ! lists:seq(1,100) end end).
+<0.930.0>
+> Child ! go.                              %% Send message to child
+go
+> receive Reply -> Reply end.              %% Receive response from child
+[1,2,3,4,5,6,7,8,9,10,11|...]
+```

_examples/3-processes.md

@@ -0,0 +1,13 @@
+---
+description: Light-weigth processes
+display: small
+---
+<!-- This file has to be 13 lines long -->
+```erlang
+> Me = self().
+<0.376.0>        %% Send msg using !
+> spawn(fun() -> Me!lists:seq(1,10) end).
+<0.930.0>
+> receive Reply -> Reply end.
+[1,2,3,4,5,6,7,8,9,10]
+```

_examples/4-lists-small.md

@@ -3,9 +3,10 @@ description: Find even numbers
 display: small
 ---
 ```erlang
--spec even(list(integer())) ->
-  list(integer()).
+-spec even(In) -> even(Out)
+  when In :: Out :: list(integer()).
 even(Numbers) ->
+  %% Use list comprehensions to map
   [Number || Number <- Numbers,
    Number rem 2 == 0].
 ```