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Algo/Séminaire/Chapter 4 - A bit of imperative.md

@@ -72,6 +72,12 @@ Error: should have int type (*because of the hidden else*)
 
 # let print_even n = 
 	if n mod 2 = 0 then
-		print_int n ;
-		print_newline()
-		
+		begin
+			print_int n ;
+			print_newline()
+		end;; (*begin and end used to execute more than 1 function into a if*)
+val print_even : int -> unit = <fun>
+
+# print_even 4;;
+4
+-: unit = ()

Algo/Séminaire/Chapter 5 - Recursivity.md

@@ -0,0 +1,44 @@
+![[recursivite-meme.png]]
+### 5.1. Simple functions
+To create a recursive function we have to use this structure
+
+```Ocaml
+(*normal function*)
+# let f = expr -> 1) evaluate expr ; 2) create & link f to the result
+
+(*recursiv function*)
+# let rec f = expr -> 1) create f ; 2) evaluate expr ; 3) link f to the result
+```
+
+**Exmple with factorial function**
+```Ocaml
+# let rec fact = function 
+	| 0 -> 1
+	| n -> n * fact(n-1)
+
+# fact 4;;
+-: int = 24
+```
+![[fact function response.png]]
+> ⚠️ CAML have a call stack limite (it will block with stack overflow if the limit is reach)
+
+**Basic expression**
+```Ocaml
+let rec f params = 
+	if stop condition then 
+		stop expression
+	else
+		recursive expression 
+```
+
+To write a recurvise function we need two things
+1) There always is a stop case
+2) The parameters of a recursive call are different then its parent call, and go towards  the stop condition
+
+### 5.2. Down
+```Ocaml
+# let rec countdown n = 
+	if n = 0 then
+		print_int(0)
+	else
+		print_int(countdown (n-1));;