make BigInt.fromFloat error-safe (#7419)

* make fromFloat error-safe

fixes #7089

⚠️ breaking change

* shadow rather than prefix with underscore

Author: bloodyowl

CHANGELOG.md

@@ -15,6 +15,7 @@
 #### :boom: Breaking Change
 
 - Rename `JsError` to `JsExn` and error modules cleanup. https://github.com/rescript-lang/rescript/pull/7408
+- Make `BigInt.fromFloat` return an option rather than throwing an error in case it's passed a value with a decimal value. https://github.com/rescript-lang/rescript/pull/7419
 
 #### :rocket: New Feature
 

lib/es6/Stdlib_BigInt.js

@@ -1,6 +1,14 @@
 
 
 
+function fromFloat(value) {
+  try {
+    return BigInt(value);
+  } catch (exn) {
+    return;
+  }
+}
+
 function toInt(t) {
   return Number(t) | 0;
 }
@@ -10,6 +18,7 @@ function bitwiseNot(x) {
 }
 
 export {
+  fromFloat,
   toInt,
   bitwiseNot,
 }

lib/js/Stdlib_BigInt.js

@@ -1,6 +1,14 @@
 'use strict';
 
 
+function fromFloat(value) {
+  try {
+    return BigInt(value);
+  } catch (exn) {
+    return;
+  }
+}
+
 function toInt(t) {
   return Number(t) | 0;
 }
@@ -9,6 +17,7 @@ function bitwiseNot(x) {
   return x ^ -1n;
 }
 
+exports.fromFloat = fromFloat;
 exports.toInt = toInt;
 exports.bitwiseNot = bitwiseNot;
 /* No side effect */

runtime/Stdlib_BigInt.res

@@ -37,6 +37,12 @@ external fromStringExn: string => bigint = "BigInt"
 @val external fromInt: int => bigint = "BigInt"
 @val external fromFloat: float => bigint = "BigInt"
 
+let fromFloat = (value: float) => {
+  try Some(fromFloat(value)) catch {
+  | _ => None
+  }
+}
+
 @send
 /**
 Formats a `bigint` as a string. Return a `string` representing the given value.

tests/tests/src/core/Core_TempTests.mjs

@@ -140,7 +140,7 @@ console.info("BigInt");
 
 console.info("---");
 
-console.log(Primitive_bigint.div(BigInt(1), BigInt(12.0)));
+console.log(Primitive_bigint.div(BigInt(1), Stdlib_Option.getOr(Stdlib_BigInt.fromFloat(12.0), 0n)));
 
 console.info("");
 

tests/tests/src/core/Core_TempTests.res

@@ -77,7 +77,7 @@ Console.info("---")
 @warning("-44")
 Console.log({
   open BigInt
-  fromInt(1) / fromFloat(12.0)
+  fromInt(1) / fromFloat(12.0)->Option.getOr(0n)
 })
 
 Console.info("")

tests/tests/src/core/Core_TestTests.mjs

@@ -2,11 +2,13 @@
 
 import * as Test from "./Test.mjs";
 import * as Pervasives from "rescript/lib/es6/Pervasives.js";
+import * as Stdlib_BigInt from "rescript/lib/es6/Stdlib_BigInt.js";
+import * as Stdlib_Option from "rescript/lib/es6/Stdlib_Option.js";
 import * as Primitive_object from "rescript/lib/es6/Primitive_object.js";
 
 let eq = Primitive_object.equal;
 
-let bign = BigInt(Number.MAX_VALUE);
+let bign = Stdlib_Option.getOr(Stdlib_BigInt.fromFloat(Number.MAX_VALUE), 0n);
 
 let bign$1 = bign + bign;
 

tests/tests/src/core/Core_TestTests.res

@@ -1,6 +1,6 @@
 let eq = (a, b) => a == b
 
-let bign = BigInt.fromFloat(Float.Constants.maxValue)
+let bign = BigInt.fromFloat(Float.Constants.maxValue)->Option.getOr(0n)
 let bign = BigInt.add(bign, bign)
 
 Test.run(__POS_OF__("print null"), Test.print(null), eq, "null")