From 67d6fb1ce37c1f2f0bd57f2fd62bf31d2d94cde3 Mon Sep 17 00:00:00 2001
From: "Victor Wang(wang shaojie)" <wang_shaojie@icloud.com>
Date: Tue, 11 Sep 2018 19:09:43 +0800
Subject: [PATCH 1/2] add create, filter_opt, reduce, merge for RList

---
 __tests__/RList_test.re | 26 ++++++++++++++++++++++++-
 src/RList.re            | 42 ++++++++++++++++++++++++++++++++++++++++-
 src/RList.rei           | 10 +++++++++-
 3 files changed, 75 insertions(+), 3 deletions(-)

diff --git a/__tests__/RList_test.re b/__tests__/RList_test.re
index 1ceccdc..5f57343 100644
--- a/__tests__/RList_test.re
+++ b/__tests__/RList_test.re
@@ -278,4 +278,28 @@ test("difference", () => expect(difference([1, 2, 3], [3, 4, 5])) |> toEqual([1,
 
 test("intersection", () => expect(intersection([1, 2, 3], [3, 4, 5])) |> toEqual([3]));
 
-test("zip", () => expect(zip([1, 2, 3], [4, 5, 6])) |> toEqual([(1, 4), (2, 5), (3, 6)]));
\ No newline at end of file
+test("zip", () => expect(zip([1, 2, 3], [4, 5, 6])) |> toEqual([(1, 4), (2, 5), (3, 6)]));
+
+test("create", () =>
+  expect((create(x => x, -1), create(x => x * 2, 4)))
+  |> toEqual(([], [0, 2, 4, 6]))
+);
+
+test("filter_opt", () =>
+  expect((
+    filter_opt([]),
+    filter_opt([Some(3), None, Some(4), None, Some(5)]),
+  ))
+  |> toEqual(([], [3, 4, 5]))
+);
+
+test("reduce", () =>
+  expect((reduce((+), []), reduce((+), [1, 2, 3])))
+  |> toEqual((None, Some(6)))
+);
+
+test("merge", () => {
+  let compare = (a, b) => a - b;
+  expect((merge(compare, [], []), merge(compare, [1, 3, 5], [2, 4])))
+  |> toEqual(([], [1, 2, 3, 4, 5]));
+});
\ No newline at end of file
diff --git a/src/RList.re b/src/RList.re
index 2b52536..b4a819c 100644
--- a/src/RList.re
+++ b/src/RList.re
@@ -353,4 +353,44 @@ let filter_map = (pred, f, xs) =>
 let filter_mapi = (pred, f, xs) =>
   fold_lefti((acc, i, a) => pred(i, a) ? append(f(i, a), acc) : acc, [], xs);
 
-let pure = (a) => [a];
\ No newline at end of file
+let pure = (a) => [a];
+
+let create = (f, n) =>
+  if (n < 0) {
+    [];
+  } else {
+    let rec loop = (n, acc) =>
+      n == 0 ? acc : loop(n - 1, [f(n - 1), ...acc]);
+    loop(n, []);
+  };
+
+let filter_opt = xs => {
+  let rec loop = (l, acc) =>
+    switch (l) {
+    | [] => acc
+    | [hd, ...tl] =>
+      switch (hd) {
+      | None => loop(tl, acc)
+      | Some(x) => loop(tl, [x, ...acc])
+      }
+    };
+  List.rev(loop(xs, []));
+};
+
+let reduce = (f, xs) =>
+  switch (xs) {
+  | [] => None
+  | [hd, ...tl] => Some(List.fold_left(f, hd, tl))
+  };
+
+let merge = (compare, xs, ys) => {
+  let rec loop = (acc, xs, ys) =>
+    switch (xs, ys) {
+    | ([], ys) => List.rev_append(acc, ys)
+    | (xs, []) => List.rev_append(acc, xs)
+    | ([h1, ...t1], [h2, ...t2]) =>
+      compare(h1, h2) <= 0 ?
+        loop([h1, ...acc], t1, ys) : loop([h2, ...acc], xs, t2)
+    };
+  loop([], xs, ys);
+};
\ No newline at end of file
diff --git a/src/RList.rei b/src/RList.rei
index 5992525..ac8073a 100644
--- a/src/RList.rei
+++ b/src/RList.rei
@@ -149,4 +149,12 @@ let filteri: ((int, 'a) => bool, list('a)) => list('a);
 
 let filter_map: ('a => bool, 'a => 'b, list('a)) => list('b);
 
-let filter_mapi: ((int, 'a) => bool, (int, 'a) => 'b, list('a)) => list('b);
\ No newline at end of file
+let filter_mapi: ((int, 'a) => bool, (int, 'a) => 'b, list('a)) => list('b);
+
+let create: (int => 'a, int) => list('a);
+
+let filter_opt: list(option('a)) => list('a);
+
+let reduce: (('a, 'a) => 'a, list('a)) => option('a);
+
+let merge: (('a, 'a) => int, list('a), list('a)) => list('a);
\ No newline at end of file

From 8ea0fa6f2d14eac60d1212cf1c34febd759a7b05 Mon Sep 17 00:00:00 2001
From: "Victor Wang(wang shaojie)" <wang_shaojie@icloud.com>
Date: Sun, 23 Sep 2018 20:03:05 +0800
Subject: [PATCH 2/2] create tryWith for Option

---
 __tests__/Option_test.re | 6 +++++-
 src/Option.re            | 5 +++++
 src/Option.rei           | 2 ++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/__tests__/Option_test.re b/__tests__/Option_test.re
index 1f3915e..9b8ef6e 100644
--- a/__tests__/Option_test.re
+++ b/__tests__/Option_test.re
@@ -86,4 +86,8 @@ describe(
       }
     )
   }
-);
\ No newline at end of file
+);
+
+test("tryWith", () => expect((tryWith(() => raise(Not_found)), tryWith(() => 3)))
+  |> toEqual((None, Some(3)))
+)
\ No newline at end of file
diff --git a/src/Option.re b/src/Option.re
index fea6c8e..656e972 100644
--- a/src/Option.re
+++ b/src/Option.re
@@ -40,6 +40,11 @@ let firstSome = (a, b) =>
   | _ => a
   };
 
+let tryWith = f =>
+  try (Some(f())) {
+  | _ => None
+  };
+
 include Monad.MakeBasic({
   type t('a) = option('a);
   let bind = (o, f) =>
diff --git a/src/Option.rei b/src/Option.rei
index d8b7379..f7df4dc 100644
--- a/src/Option.rei
+++ b/src/Option.rei
@@ -14,6 +14,8 @@ let toExn: (string, option('a)) => 'a;
 
 let firstSome: (option('a), option('a)) => option('a);
 
+let tryWith: (unit => 'a) => option('a);
+
 include Monad.Basic with type t('a) := option('a);
 
 include Applicative.Basic with type t('a) := option('a);