use dune_site module to find inputs

this packages the inputs as part of the build and exposes the directory
to find them via a generated module. this way, inputs are a resource of
the library rather than an input.

this means that `dune exec aoc` and `dune utop` will always find the
file regardless of where they are invoked, which makes developing in
emacs simpler :)

src/day1.ml

@@ -24,7 +24,7 @@ let part2 lines =
 ;;
 
 let print () =
-  let lines = Utils.lines_of_file "inputs/day1.tt" in
+  let lines = Utils.lines_of_input 1 in
   Printf.(
     printf "Day 1.1: %d\n" @@ part1 lines;
     printf "Day 1.2: %d\n" @@ part2 lines)

src/day2.ml

@@ -87,7 +87,7 @@ let part2 lines =
 ;;
 
 let print () =
-  let lines = Utils.lines_of_file "./inputs/day2.tt" in
+  let lines = Utils.lines_of_input 2 in
   Printf.(
     printf "Day 2.1: %d\n" @@ part1 lines;
     printf "Day 2.2: %d\n" @@ part2 lines)

src/dune

@@ -1,4 +1,12 @@
 (library
  (name aoc)
- (libraries stdio re)
+ (libraries stdio re dune-site)
  (preprocess (pps ppx_regexp)))
+
+(install
+ (section (site (aoc inputs)))
+ (files (glob_files ../inputs/*)))
+
+(generate_sites_module
+ (module inputs)
+ (sites aoc))

src/utils.ml

@@ -1,9 +1,9 @@
-let lines_of_file filename = Stdio.In_channel.(with_file filename ~f:input_lines)
-
-let rec print_int_list = function
-  | [] -> ()
-  | e :: l ->
-    print_int e;
-    print_string " ";
-    print_int_list l
+let lines_of_input day =
+  let base_path =
+    match Inputs.Sites.inputs with
+    | path :: _ -> path
+    | _ -> failwith "cant find sites path"
+  in
+  let path = Printf.sprintf "%s/day%d.tt" base_path day in
+  Stdio.In_channel.(with_file path ~f:input_lines)
 ;;