Add number round (#3533)

.changeset/quick-roses-warn.md

@@ -0,0 +1,6 @@
+---
+"effect": minor
+"@effect/cli": patch
+---
+
+Add Number.round

packages/cli/src/internal/prompt/number.ts

@@ -5,6 +5,7 @@ import * as Optimize from "@effect/printer/Optimize"
 import * as Schema from "@effect/schema/Schema"
 import * as Arr from "effect/Array"
 import * as Effect from "effect/Effect"
+import * as EffectNumber from "effect/Number"
 import * as Option from "effect/Option"
 import type * as Prompt from "../../Prompt.js"
 import * as InternalPrompt from "../prompt.js"
@@ -20,11 +21,6 @@ interface State {
   readonly error: Option.Option<string>
 }
 
-const round = (number: number, precision: number) => {
-  const factor = Math.pow(10, precision)
-  return Math.round(number * factor) / factor
-}
-
 const parseInt = Schema.NumberFromString.pipe(
   Schema.int(),
   Schema.decodeUnknown
@@ -352,7 +348,7 @@ function handleProcessFloat(options: FloatOptions) {
             })),
           onSuccess: (n) =>
             Effect.flatMap(
-              Effect.sync(() => round(n, options.precision)),
+              Effect.sync(() => EffectNumber.round(n, options.precision)),
               (rounded) =>
                 Effect.match(options.validate(rounded), {
                   onFailure: (error) =>

packages/effect/src/Number.ts

@@ -492,3 +492,26 @@ export const parse = (s: string): Option<number> => {
     ? option.none
     : option.some(n)
 }
+
+/**
+ * Returns the number rounded with the given precision.
+ *
+ * @param self - The number to round
+ * @param precision - The precision
+ *
+ * @example
+ * import { round } from "effect/Number"
+ *
+ * assert.deepStrictEqual(round(1.1234, 2), 1.12)
+ * assert.deepStrictEqual(round(1.567, 2), 1.57)
+ *
+ * @category math
+ * @since 3.8.0
+ */
+export const round: {
+  (precision: number): (self: number) => number
+  (self: number, precision: number): number
+} = dual(2, (self: number, precision: number): number => {
+  const factor = Math.pow(10, precision)
+  return Math.round(self * factor) / factor
+})

packages/effect/test/Number.test.ts

@@ -135,4 +135,13 @@ describe("Number", () => {
     assert.deepStrictEqual(Number.parse("42"), Option.some(42))
     assert.deepStrictEqual(Number.parse("a"), Option.none())
   })
+
+  it("round", () => {
+    assert.deepStrictEqual(Number.round(1.1234, 2), 1.12)
+    assert.deepStrictEqual(Number.round(2)(1.1234), 1.12)
+    assert.deepStrictEqual(Number.round(0)(1.1234), 1)
+    assert.deepStrictEqual(Number.round(0)(1.1234), 1)
+    assert.deepStrictEqual(Number.round(1.567, 2), 1.57)
+    assert.deepStrictEqual(Number.round(2)(1.567), 1.57)
+  })
 })