84 lines
1.8 KiB
Markdown
84 lines
1.8 KiB
Markdown
## 0.1. Print
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If we want to print something in CAML, we have to use this structure
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```Ocaml
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# print_string "Hello World!";;
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Hello! - : unit=()
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# print_int ;;
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-: int -> unit = <fun>
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(*expression*)
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# print_[type] [things to print];;
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[things to print] -: unit=()
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```
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**Difference between compiler and interpreter for print**
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```mermaid
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flowchart LR
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A[CAML] -- compile --> B[ ] -- exec --> C[standard output] & D[standard error] ~~~ E(on your terminal)
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```
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```mermaid
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flowchart LR
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A[CAML] -- interpreter --> B[standard error] & C[standard output] & D[CAML answer] ~~~ E(in the interpreter interface)
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```
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**To print something and create a new line for the CAML evaluation**
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```Ocaml
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# print_endline "toto";;
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toto
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-: unit = ()
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```
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**To just print a newline**
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```Ocaml
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# print_newline();;
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-: unit = ()
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```
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## 0.2. Sequence of prints
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To print two things on the same line we have to use this structure
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```Ocaml
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# print_string "The answer is: "; print_int 42;;
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The answer is: 42 -: unit = ()
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# 3*2*7; print_string "The answer is : ";;
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The answer is -: unit = ()
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Warning 10 [non-unit-statement]: this expression should have type unit.
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# print_string "The answer is: "; 3*2*7;;
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The answer is: -:int = 42
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```
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### 0.3. Print in a function
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```OCaml
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# let print_even n =
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if n mod 2 = 0 then
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print_int n;;
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(*Caml will automaticaly add the else with a empty value ()*)
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val print_even: int -> unit = <fun>
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# print_even 4;;
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4 -: unit = ()
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# print_even 7;;
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-: unit = ()
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# let ret_even n =
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if n mod 2 = 0 then
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n;;
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Error: should have int type (*because of the hidden else*)
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# let print_even n =
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if n mod 2 = 0 then
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begin
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print_int n ;
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print_newline()
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end;; (*begin and end used to execute more than 1 function into a if*)
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val print_even : int -> unit = <fun>
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# print_even 4;;
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4
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-: unit = ()
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