Provide a fib implementation for jlouis

Most of the entry is pure build-scaffolding. The meat is in a single
file, which is then referenced in people.json.

8 files changed, 107 insertions, 0 deletions

diff --git a/entries/jlouis/README.md b/entries/jlouis/README.md
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+# Fib like only I would write it
+
+## Instructions
+
+Everything is in `bin/fib.ml` and the rest is just scaffolding.
+
+Use nix to get an OCaml development environment.
+
+Use dune to build: `dune build`
+Use dune to run: `dune exec fib`
+Use dune to test: `dune test`
diff --git a/entries/jlouis/bin/dune b/entries/jlouis/bin/dune
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+(executable
+ (public_name fib)
+ (name main)
+ (libraries fib))
diff --git a/entries/jlouis/bin/main.ml b/entries/jlouis/bin/main.ml
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+let _ = print_endline ("Mok'ra: " ^ string_of_int (Fib.Orc.iter 10))
\ No newline at end of file
diff --git a/entries/jlouis/dune-project b/entries/jlouis/dune-project
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+++ b/entries/jlouis/dune-project
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+(lang dune 3.4)
+
+(name fib)
diff --git a/entries/jlouis/fib.opam b/entries/jlouis/fib.opam
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--- /dev/null
+++ b/entries/jlouis/fib.opam
diff --git a/entries/jlouis/lib/dune b/entries/jlouis/lib/dune
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+(library
+ (name fib)
+ (inline_tests)
+ (preprocess
+  (pps ppx_inline_test)))
diff --git a/entries/jlouis/lib/fib.ml b/entries/jlouis/lib/fib.ml
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+++ b/entries/jlouis/lib/fib.ml
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+module type BASIS =
+  sig
+    type t
+    val one : t
+    val out : t -> int
+    val to_string : t -> string
+  end
+
+module type MONOIDIC =
+  sig
+    include BASIS
+    val concat : t -> t -> t
+  end
+
+(* Single Tuple, Multiple Data *)
+module STMD : MONOIDIC =
+  struct
+    type t = int * int * int * int
+
+    let one = (1, 1,
+               1, 0)
+
+    let out (_, _, _, x) = x
+
+    let to_string (a,b,c,d) = "(" ^ (string_of_int a) ^ ", "
+                                  ^ (string_of_int b) ^ ", "
+                                  ^ (string_of_int c) ^ ", "
+                                  ^ (string_of_int d) ^ ")"
+
+    let concat (a11, a12, a21, a22) (b11, b12, b21, b22) =
+      let muladd a x b y = (a*x) + (b*y) in
+      (muladd a11 b11 a12 b21,
+       muladd a11 b12 a12 b22,
+       muladd a21 b11 a22 b21,
+       muladd a21 b12 a22 b22)
+  end
+
+module MkLinear(M : MONOIDIC) =
+  struct
+    let iter n =
+      let rec loop n acc =
+        match n with
+        | 0 -> acc
+        | k -> loop (k-1) (M.concat M.one acc)
+      in
+        M.out (loop n M.one)
+
+  end
+
+module MkLog(M : MONOIDIC) =
+  struct
+    let iter n =
+      let rec loop y x k =
+        if k = 0 then y
+        else if k mod 2 = 0 then loop y (M.concat x x) (k/2)
+                            else loop (M.concat y x) (M.concat x x) ((k-1)/2)
+      in
+        M.out (loop M.one M.one n)
+  end
+
+module Kobold = MkLinear(STMD) (* You no take candle! *)
+module Orc = MkLog(STMD) (* Mok'ra *)
+
+let%test _ = Kobold.iter 10 = 55
+let%test _ = Kobold.iter 0 = 0
+let%test _ = Orc.iter 0 = 0
+let%test _ = Orc.iter 1 = 1
+let%test _ = Orc.iter 2 = 1
+let%test _ = Orc.iter 3 = 2
+let%test _ = Orc.iter 4 = 3
+let%test _ = Orc.iter 5 = 5
+let%test _ = Orc.iter 10 = 55
diff --git a/entries/jlouis/shell.nix b/entries/jlouis/shell.nix
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+let
+ pkgs = import <nixpkgs> {};
+ # choose the ocaml version you want to use
+ ocamlPackages = pkgs.ocaml-ng.ocamlPackages_4_14;
+in
+pkgs.mkShell {
+  # build tools
+  nativeBuildInputs = with ocamlPackages; [ ocaml utop findlib dune_3 ocaml-lsp ppx_inline_test ];
+  # dependencies
+  buildInputs = with ocamlPackages; [ ocamlgraph ];
+}