Change ieee_float.to_finite to return a Result

README.md

@@ -49,9 +49,9 @@ pub fn main() {
   let assert True = ieee_float.is_nan(nan)
 
   // Convert to a finite value of type `Float`. If the IEEE float is not
-  // finite then the fallback value is returned.
-  let assert 1.0 = ieee_float.to_finite(one, 5.0)
-  let assert 5.0 = ieee_float.to_finite(positive_inf, 5.0)
+  // finite then an error is returned.
+  let assert Ok(1.0) = ieee_float.to_finite(one)
+  let assert Error(Nil) = ieee_float.to_finite(positive_inf)
 
   // Convert a value to raw bytes
   let assert <<0x3F, 0x80, 0x00, 0x00>> = ieee_float.to_bytes_32_be(one)

src/ieee_float.gleam

@@ -71,13 +71,13 @@ pub fn is_nan(f: IEEEFloat) -> Bool {
 }
 
 /// Converts an `IEEEFloat` to the native `Float` type. If the `IEEEFloat` is
-/// infinite or `NaN` then `fallback` is returned.
+/// infinite or `NaN` then `Error(Nil)` is returned.
 ///
 @external(javascript, "./ieee_float_js.mjs", "to_finite")
-pub fn to_finite(f: IEEEFloat, fallback: Float) -> Float {
+pub fn to_finite(f: IEEEFloat) -> Result(Float, Nil) {
   case f {
-    Finite(value) -> value
-    _ -> fallback
+    Finite(value) -> Ok(value)
+    _ -> Error(Nil)
   }
 }
 

src/ieee_float_js.mjs

@@ -32,8 +32,8 @@ export function is_nan(f) {
   return Number.isNaN(f);
 }
 
-export function to_finite(f, fallback) {
-  return Number.isFinite(f) ? f : fallback;
+export function to_finite(f) {
+  return Number.isFinite(f) ? new Ok(f) : new Error(Nil);
 }
 
 export function to_string(f) {

test/ieee_float_test.gleam

@@ -47,20 +47,20 @@ pub fn nan_test() {
 
 pub fn to_finite_test() {
   finite(1.0)
-  |> ieee_float.to_finite(2.0)
-  |> expect.to_equal(1.0)
+  |> ieee_float.to_finite
+  |> expect.to_equal(Ok(1.0))
 
   positive_infinity()
-  |> ieee_float.to_finite(2.0)
-  |> expect.to_equal(2.0)
+  |> ieee_float.to_finite
+  |> expect.to_equal(Error(Nil))
 
   negative_infinity()
-  |> ieee_float.to_finite(2.0)
-  |> expect.to_equal(2.0)
+  |> ieee_float.to_finite
+  |> expect.to_equal(Error(Nil))
 
   nan()
-  |> ieee_float.to_finite(2.0)
-  |> expect.to_equal(2.0)
+  |> ieee_float.to_finite
+  |> expect.to_equal(Error(Nil))
 }
 
 pub fn to_string_test() {