Merge pull request #50 from adnelson/flatMapOkPure

add flatMapOkPure function & tests
RationalJS · Jul 12, 2020 · 9559b90 · 9559b90
2 parents 66ca4ad + d37a8a6
commit 9559b90
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diff --git a/__tests__/TestFuture.re b/__tests__/TestFuture.re
@@ -184,6 +184,27 @@ describe("Future Belt.Result", () => {
       )
   );
 
+  testAsync("flatMapOkPure 1", finish =>
+    Belt.Result.Ok("four")
+    ->Future.value
+    ->Future.flatMapOkPure(s => Belt.Result.Ok(s ++ "!"))
+    ->Future.get(r =>
+        Belt.Result.getExn(r) |> expect |> toEqual("four!") |> finish
+      )
+  );
+
+  testAsync("flatMapOkPure 2", finish =>
+    Belt.Result.Error("err4.1")
+    ->Future.value
+    ->Future.flatMapOkPure(s => Belt.Result.Ok(s ++ "!"))
+    ->Future.get(r =>
+        switch (r) {
+        | Ok(_) => fail("shouldn't be possible") |> finish
+        | Error(e) => e |> expect |> toEqual("err4.1") |> finish
+        }
+      )
+  );
+
   testAsync("flatMapError 1", finish =>
     Belt.Result.Ok("five")
     ->Future.value

diff --git a/src/Future.re b/src/Future.re
@@ -121,6 +121,8 @@ let flatMapOk = (future, f) =>
     }
   );
 
+let flatMapOkPure = (fut, f) => fut->flatMapOk(result => value(result->f));
+
 let flatMapError = (future, f) =>
   future->flatMap(r =>
     switch (r) {
@@ -163,4 +165,5 @@ let delay = (~executor=?, ms, f) =>
 let sleep = (~executor=?, ms) => delay(~executor?, ms, () => ());
 
 let (>>=) = flatMapOk;
+let (>>==) = flatMapOkPure;
 let (<$>) = mapOk;
diff --git a/src/Future.rei b/src/Future.rei
@@ -19,6 +19,9 @@ let mapError:
 let flatMapOk:
   (t(Belt.Result.t('a, 'b)), 'a => t(Belt.Result.t('c, 'b))) =>
   t(Belt.Result.t('c, 'b));
+let flatMapOkPure:
+  (t(Belt.Result.t('a, 'b)), 'a => Belt.Result.t('c, 'b)) =>
+  t(Belt.Result.t('c, 'b));
 let flatMapError:
   (t(Belt.Result.t('a, 'b)), 'b => t(Belt.Result.t('a, 'c))) =>
   t(Belt.Result.t('a, 'c));
@@ -45,4 +48,7 @@ let sleep: (~executor: executorType=?, int) => t(unit);
 let ( >>= ):
   (t(Belt.Result.t('a, 'b)), 'a => t(Belt.Result.t('c, 'b))) =>
   t(Belt.Result.t('c, 'b));
+let ( >>== ):
+  (t(Belt.Result.t('a, 'b)), 'a => Belt.Result.t('c, 'b)) =>
+  t(Belt.Result.t('c, 'b));
 let ( <$> ): (t(Belt.Result.t('a, 'b)), 'a => 'c) => t(Belt.Result.t('c, 'b));