--- a/2023/aoc23/aoc23.opam	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,34 +0,0 @@
-# This file is generated by dune, edit dune-project instead
-opam-version: "2.0"
-synopsis: "A short synopsis"
-description: "A longer description"
-maintainer: ["Maintainer Name"]
-authors: ["Author Name"]
-license: "LICENSE"
-tags: ["topics" "to describe" "your" "project"]
-homepage: "https://github.com/username/reponame"
-doc: "https://url/to/documentation"
-bug-reports: "https://github.com/username/reponame/issues"
-depends: [
-  "ocaml"
-  "dune" {>= "3.10"}
-  "base"
-  "core"
-  "stdio"
-  "odoc" {with-doc}
-]
-build: [
-  ["dune" "subst"] {dev}
-  [
-    "dune"
-    "build"
-    "-p"
-    name
-    "-j"
-    jobs
-    "@install"
-    "@runtest" {with-test}
-    "@doc" {with-doc}
-  ]
-]
-dev-repo: "git+https://github.com/username/reponame.git"

--- a/2023/aoc23/bin/day01.ml	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +0,0 @@
-

--- a/2023/aoc23/bin/dune	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,5 +0,0 @@
-(executable
- (public_name aoc23)
- (name main)
- (libraries aoc23))
-

--- a/2023/aoc23/bin/main.ml	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +0,0 @@
-let () = print_endline "Hello, World!"

--- a/2023/aoc23/day01.ml	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,111 +0,0 @@
-open Stdio
-open Base
-
-let input () = In_channel.stdin
-
-(* Part 1 *)
-module Part1 = struct
-  let calibration_value_of_string s =
-    let digits = String.filter s ~f:Char.is_digit in
-    let first, last = (String.prefix digits 1, String.suffix digits 1) in
-    Int.of_string (String.concat [ first; last ])
-
-  let process ch =
-    let f lines line = calibration_value_of_string line :: lines in
-    List.rev @@ In_channel.fold_lines ch ~init:[] ~f
-
-  let _part1 () =
-    let r = process (input ()) in
-    Out_channel.printf "%d\n" (List.fold ~init:0 ~f:( + ) r)
-end
-
-(* Part 2 *)
-
-module Part2 = struct
-  let folder ix acc x : (int * int) option =
-    match (ix, acc, x) with
-    | ix, None, d ->
-        let i = Int.of_string_opt (String.of_char d) in
-        Option.map i ~f:(fun i -> (ix, i))
-    | _, Some d, _ -> Some d
-
-  (* Return the (index, value) of the first digit in the string *)
-  let find_first_digit s = String.foldi ~init:None ~f:folder s
-
-  (* Return the (index, value) of the last digit in the string *)
-  let find_last_digit s : (int * int) option =
-    let%map.Option ix, v = find_first_digit (String.rev s) in
-    (String.length s - ix - 1, v)
-
-  let digits =
-    [
-      (1, "one");
-      (2, "two");
-      (3, "three");
-      (4, "four");
-      (5, "five");
-      (6, "six");
-      (7, "seven");
-      (8, "eight");
-      (9, "nine");
-    ]
-
-  (* generate a counting sequence *)
-  let count_seq (from : int) (upto : int) : int Sequence.t =
-    let f c =
-      if Int.equal c upto then None
-      else Some (c, if upto > from then c + 1 else c - 1)
-    in
-    Sequence.unfold ~init:from ~f
-
-  (* try to find number string `number` with value `value` in string `s`, from the beginning if `fwd`. *)
-  let find_number ~fwd s value number : int option * int =
-    let ixs =
-      if fwd then count_seq 0 (String.length s)
-      else count_seq (String.length s - 1) 0
-    in
-    let check pos = String.is_substring_at s ~pos ~substring:number in
-    (Sequence.find ixs ~f:check, value)
-
-  (* find any number word in the string, from the beginning if `fwd` or from the end otherwise. *)
-  let find_any_number ~fwd s : (int * int) option =
-    let f (value, number) = find_number ~fwd s value number in
-    let found = List.map digits ~f in
-    let compare (ix1, _) (ix2, _) =
-      match (ix1, ix2) with
-      | Some a, Some b -> Int.compare a b * if fwd then 1 else -1
-      | Some _, None -> -1
-      | None, Some _ -> 1
-      | None, None -> 0
-    in
-    (* sort by index *)
-    let sorted = List.sort found ~compare in
-    match List.hd_exn sorted with Some ix, d -> Some (ix, d) | None, _ -> None
-
-  (* Process line `line`, and return numeric result. *)
-  let handle line : int =
-    let maybe_first_dig = find_first_digit line in
-    let maybe_first_wrd = find_any_number ~fwd:true line in
-    let maybe_last_dig = find_last_digit line in
-    let maybe_last_wrd = find_any_number ~fwd:false line in
-    let match_num ~fwd (dig : (int * int) option) (wrd : (int * int) option) =
-      match (dig, wrd) with
-      | Some (ix1, d1), Some (ix2, d2) ->
-          if (fwd && ix1 < ix2) || ((not fwd) && ix1 > ix2) then d1 else d2
-      | Some (_, d), None | None, Some (_, d) -> d
-      | None, None -> assert false
-    in
-    let first_dig = match_num ~fwd:true maybe_first_dig maybe_first_wrd in
-    let last_dig = match_num ~fwd:false maybe_last_dig maybe_last_wrd in
-    (10 * first_dig) + last_dig
-
-  let process ch =
-    let f lines line = handle line :: lines in
-    List.rev @@ In_channel.fold_lines ch ~init:[] ~f
-
-  let part2 () =
-    let r = process In_channel.stdin in
-    Out_channel.printf "%d\n" (List.fold ~init:0 ~f:( + ) r)
-end
-
-let () = Part2.part2 ()

--- a/2023/aoc23/dune	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,5 +0,0 @@
-(executable
- (name day01)
- (libraries base core)
- (preprocess (pps ppx_let))
- )

--- a/2023/aoc23/dune-project	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,26 +0,0 @@
-(lang dune 3.10)
-
-(name aoc23)
-
-(generate_opam_files true)
-
-(source
- (github username/reponame))
-
-(authors "Author Name")
-
-(maintainers "Maintainer Name")
-
-(license LICENSE)
-
-(documentation https://url/to/documentation)
-
-(package
- (name aoc23)
- (synopsis "A short synopsis")
- (description "A longer description")
- (depends ocaml dune base core stdio)
- (tags
-  (topics "to describe" your project)))
-
-; See the complete stanza docs at https://dune.readthedocs.io/en/stable/dune-files.html#dune-project

--- a/2023/aoc23/lib/dune	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,2 +0,0 @@
-(library
- (name aoc23))

--- a/2023/aoc23/test/dune	Sat Dec 02 13:53:44 2023 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,2 +0,0 @@
-(test
- (name aoc23))

--- a/2023/day01.ml	Sat Dec 02 13:53:44 2023 +0100
+++ b/2023/day01.ml	Sat Dec 02 14:02:37 2023 +0100
@@ -58,6 +58,7 @@
     in
     Sequence.unfold ~init:from ~f
 
+  (* try to find number string `number` with value `value` in string `s`, from the beginning if `fwd`. *)
   let find_number ~fwd s value number : int option * int =
     let ixs =
       if fwd then count_seq 0 (String.length s)
@@ -66,6 +67,7 @@
     let check pos = String.is_substring_at s ~pos ~substring:number in
     (Sequence.find ixs ~f:check, value)
 
+  (* find any number word in the string, from the beginning if `fwd` or from the end otherwise. *)
   let find_any_number ~fwd s : (int * int) option =
     let f (value, number) = find_number ~fwd s value number in
     let found = List.map digits ~f in
@@ -80,7 +82,8 @@
     let sorted = List.sort found ~compare in
     match List.hd_exn sorted with Some ix, d -> Some (ix, d) | None, _ -> None
 
-  let handle line =
+  (* Process line `line`, and return numeric result. *)
+  let handle line : int =
     let maybe_first_dig = find_first_digit line in
     let maybe_first_wrd = find_any_number ~fwd:true line in
     let maybe_last_dig = find_last_digit line in