JS float functions

2 files changed, 80 insertions, 28 deletions

diff --git a/src/gleam/float.gleam b/src/gleam/float.gleam
index 8fdb79e..1191ac1 100644
--- a/src/gleam/float.gleam
+++ b/src/gleam/float.gleam
@@ -97,40 +97,80 @@ pub fn max(a: Float, b: Float) -> Float {
   }
 }
 
+/// Rounds the value to the next highest whole number as a float.
+///
+/// ## Examples
+///
+///    > ceiling(2.3)
+///    3.0
+///
+pub fn ceiling(float: Float) -> Float {
+  do_ceiling(float)
+}
+
 if erlang {
-  /// Rounds the value to the next highest whole number as a float.
-  ///
-  /// ## Examples
-  ///
-  ///    > ceiling(2.3)
-  ///    3.0
-  ///
-  pub external fn ceiling(Float) -> Float =
+  external fn do_ceiling(Float) -> Float =
     "math" "ceil"
+}
 
-  /// Rounds the value to the next lowest whole number as a float.
-  ///
-  /// ## Examples
-  ///
-  ///    > floor(2.3)
-  ///    2.0
-  ///
-  pub external fn floor(Float) -> Float =
+if javascript {
+  external fn do_ceiling(Float) -> Float =
+    "../gleam_stdlib.js" "ceiling"
+}
+
+/// Rounds the value to the next lowest whole number as a float.
+///
+/// ## Examples
+///
+///    > floor(2.3)
+///    2.0
+///
+pub fn floor(float: Float) -> Float {
+  do_floor(float)
+}
+
+if erlang {
+  external fn do_floor(Float) -> Float =
     "math" "floor"
+}
 
-  /// Rounds the value to the nearest whole number as an int.
-  ///
-  /// ## Examples
-  ///
-  ///    > round(2.3)
-  ///    2
-  ///
-  ///    > round(2.5)
-  ///    3
-  ///
-  pub external fn round(Float) -> Int =
-    "erlang" "round"
+if javascript {
+  external fn do_floor(Float) -> Float =
+    "../gleam_stdlib.js" "floor"
+}
+
+/// Rounds the value to the nearest whole number as an int.
+///
+/// ## Examples
+///
+///    > round(2.3)
+///    2
+///
+///    > round(2.5)
+///    3
+///
+pub fn round(float: Float) -> Int {
+  do_round(float)
+}
 
+if erlang {
+  external fn do_round(Float) -> Int =
+    "math" "round"
+}
+
+if javascript {
+  fn do_round(float: Float) -> Int {
+    case float >=. 0.0 {
+      True -> js_round(float)
+      _ -> 0 - js_round(negate(float))
+    }
+  }
+
+  external fn js_round(Float) -> Int =
+    "../gleam_stdlib.js" "round"
+}
+
+if erlang {
   /// Returns the value as an int, truncating all decimal digits.
   ///
   /// ## Examples
diff --git a/src/gleam_stdlib.js b/src/gleam_stdlib.js
index 95fb526..8b2f131 100644
--- a/src/gleam_stdlib.js
+++ b/src/gleam_stdlib.js
@@ -224,3 +224,15 @@ export function print(string) {
     console.log(string); // We're in a browser. Newlines are mandated
   }
 }
+
+export function ceiling(float) {
+  return Math.ceil(float);
+}
+
+export function floor(float) {
+  return Math.floor(float);
+}
+
+export function round(float) {
+  return Math.round(float);
+}