Mar 07, 2019
Install on Linux
sudo apt-get update -y && apt-get upgrade -y
sudo apt-get install m4 patch ocaml -y
Install OPAM as per notes https://opam.ocaml.org/doc/Install.html
sudo apt-get install opam
else
wget https://raw.github.com/ocaml/opam/master/shell/opam_installer.sh -O - | sh -s /usr/local/bin
Install rest via opam
opam init
opam update
opam upgrade
opam switch
opam switch list-available
opam switch list-available base
opam switch create 4.12.0+mingw64c
# you could have multiple switches of same version
opam switch create myname 4.12.0+mingw64c
# issue with OCaml on debian - https://github.com/ocaml/opam/issues/3827
# NOW RESOLVED
rm -rf ~/.opam
apt install mccs
opam init --solver=mccs
opam switch create 4.10.0 --solver=mccs
This will take a few minutes.
For installed version of OCaml - get required tools/libraries via opam
opam install utop tuareg merlin user-setup dune
opam user-setup install
For OCaml on Windows (cygwin):
opam install depext depext-cygwinports
Better to use following to install packages – as it take care of dependencies.
E.g. to install sqlite3 package
opam depext -i sqlite3
https://stackoverflow.com/questions/67398198/
You can use dune to create a skeleton project
dune init proj demo
This will create a demo folder that will have the OCaml project skeleton ready to use.
cd demo
The main.ml is in the bin folder. To build and execute the project.
dune build
dune exec demo
To execute demo.ml that is in the test folder
dune test
To open project in utop
dune utop
Cheat sheet - https://ocaml.org/docs/cheat_sheets.html
User Manual - https://caml.inria.fr/pub/docs/manual-ocaml/
Core Library - https://caml.inria.fr/pub/docs/manual-ocaml/libref/index.html
https://ocaml.org/learn/tutorials/data_types_and_matching.html#Pattern-matching-on-datatypes
(* pair : int * int -> int -> int = <fun> *)
let pair k p =
match k, p with
| (1, _), _ -> 1
| _, 2 -> 222
| _, _ -> 0
The next are are the same.
(* first : int list -> string = <fun> *)
let first l =
match l with
| a :: b :: _ when a = b -> "double"
| 1 :: _ -> "one"
| _ -> "other"
let first = function
| a :: b :: _ when a = b -> "double"
| 1 :: _ -> "one"
| _ -> "other"
https://caml.inria.fr/pub/docs/manual-ocaml/libref/List.html
let a = List.init 5 (fun x -> x * 2);;
(* int list = [0; 2; 4; 6; 8] *)
List.map (fun x -> x * 2) a;;
(* int list = [0; 4; 8; 12; 16] *)
List.iter (fun x -> print_int x) a;;
(* 02468 *)
List.iteri (fun i x -> print_int (x + i)) a;;
(* 036912 *)
Avoid using for loop when List.iter can be used.
let my_list = [1;2;3;4]
let () =
for n = 0 to (List.length my_list - 1) do
print_int (List.nth my_list n)
done
(* 1234 *)
let () = List.iter print_int my_list
(* 1234 *)
https://caml.inria.fr/pub/docs/manual-ocaml/libref/Array.html
Array.make 5 1;;
(* int array = [|1; 1; 1; 1; 1|] *)
Array.init 5 (fun x -> x + 1);;
(* int array = [|1; 2; 3; 4; 5|] *)
let a = Array.make_matrix 2 3 1;; (* where x=2 y=3 *)
(* val a : int array array = [|[|1; 1; 1|]; [|1; 1; 1|]|] *)
a.(0).(0) <- 100;;
a;;
(* int array array = [|[|100; 1; 1|]; [|1; 1; 1|]|] *)
let create_grid n = Array.init n (fun y ->
Array.init n (fun x ->
y * n + x
)
)
let print_grid g =
let n = Array.length g in
for y = n-1 downto 0 do
for x = 0 to n-1 do
Printf.printf "%3i%!" g.(x).(y)
done;
Printf.printf "\n%!"
done
let a = create_grid 3
(* val a : int array array = [|[|0; 1; 2|]; [|3; 4; 5|]; [|6; 7; 8|]|] *)
let () = print_grid a
(*
2 5 8
1 4 7
0 3 6
*)
(* ~foo -- named argument *)
let div ~top y = top / y;;
(* or *)
let div ~top:x y = x / y;;
div 8 2;;
(* 4 *)
div 2 ~top:8;;
(* 4 *)
(* ?bar -- Named argument with a default. Cannot be used with last argument. *)
let f1 ?a:(aa=4) ~b c = aa + b + c;;
(* val f1 : ?a:int -> b:int -> int -> int *)
let f2 ?(a=4) ~b c = a + b + c;;
(* val f2 : ?a:int -> b:int -> int -> int *)
f1 1 2;;
(* 7 *)
f1 1 2 3;;
(* Error: This argument cannot be applied without label *)
f1 ~a:3 ~b:1 2;;
(* 6 *)
From https://github.com/lcoviedo/mirage-static-monitor/blob/master/dispatch.ml
let red fmt = Printf.sprintf ("\027[31m"^^fmt^^"\027[m")
let green fmt = Printf.sprintf ("\027[32m"^^fmt^^"\027[m")
let yellow fmt = Printf.sprintf ("\027[33m"^^fmt^^"\027[m")
let blue fmt = Printf.sprintf ("\027[36m"^^fmt^^"\027[m")
let () = printf "%s\n" (red "this is red")
let () = printf "%s\n" (green "this is green")
let () = printf "%s\n" (yellow "this is yellow")
let () = printf "%s\n" (blue "this is blue")
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