vault backup: 2023-09-12 15:45:33

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

@@ -38,6 +38,7 @@ toto
 ```
 
 ## 0.2. Sequence of prints
+To print two things on the same line we have to use this structure
 ```Ocaml
 # print_string "The answer is: "; print_int 42;;
 The answer is: 42 -: unit = ()
@@ -48,3 +49,29 @@ Warning 10 [non-unit-statement]: this expression should have type unit.
 
 # print_string "The answer is: "; 3*2*7;;
 The answer is: -:int = 42
+```
+
+### 0.3.  Print in a function
+```OCaml
+# let print_even n = 
+	if n mod 2 = 0 then
+		print_int n;;
+	(*Caml will automaticaly add the else with a empty value ()*)
+val print_even: int -> unit = <fun>
+
+# print_even 4;;
+4 -: unit = ()
+
+# print_even 7;;
+-: unit = ()
+
+# let ret_even n =
+	if n mod 2 = 0 then
+		n;;
+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()
+