add Int.range and Int.rangeWithOptions

CHANGELOG.md

@@ -24,6 +24,7 @@
 - Fixed type signatures of `reduce` and `reduceWithIndex`. https://github.com/rescript-association/rescript-core/pull/49
 - Add `panic`/`Error.panic`. https://github.com/rescript-association/rescript-core/pull/72
 - The globally available `null` value now originates from `Nullable` and not `Null`, just like the globally available `undefined` value does. https://github.com/rescript-association/rescript-core/pull/88
+- Add `Int.range` and `Int.rangeWithOptions`, https://github.com/rescript-association/rescript-core/pull/52
 
 ### Documentation
 

src/Core__Int.mjs

@@ -1,5 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
+import * as Pervasives from "rescript/lib/es6/pervasives.js";
+import * as Core__Array from "./Core__Array.mjs";
 
 function fromString(radix, x) {
   var maybeInt = radix !== undefined ? parseInt(x, radix) : parseInt(x);
@@ -10,6 +12,41 @@ function fromString(radix, x) {
   }
 }
 
+function rangeWithOptions(start, end, options) {
+  var isInverted = start > end;
+  var n = options.step;
+  var step;
+  if (n !== undefined) {
+    if (n !== 0) {
+      step = n;
+    } else {
+      if (start !== end) {
+        throw new RangeError("Incorrect range arguments");
+      }
+      step = n;
+    }
+  } else {
+    step = isInverted ? -1 : 1;
+  }
+  var length;
+  if (isInverted === step >= 0) {
+    length = 0;
+  } else if (step === 0) {
+    length = options.inclusive === true ? 1 : 0;
+  } else {
+    var range = isInverted ? start - end | 0 : end - start | 0;
+    var range$1 = options.inclusive === true ? range + 1 | 0 : range;
+    length = Math.ceil(range$1 / Pervasives.abs(step)) | 0;
+  }
+  return Core__Array.fromInitializer(length, (function (i) {
+                return start + Math.imul(i, step) | 0;
+              }));
+}
+
+function range(start, end) {
+  return rangeWithOptions(start, end, {});
+}
+
 var Constants = {
   minValue: -2147483648,
   maxValue: 2147483647
@@ -18,5 +55,7 @@ var Constants = {
 export {
   Constants ,
   fromString ,
+  range ,
+  rangeWithOptions ,
 }
 /* No side effect */

src/Core__Int.res

@@ -35,3 +35,29 @@ let fromString = (~radix=?, x) => {
 }
 
 external mod: (int, int) => int = "%modint"
+
+type rangeOptions = {step?: int, inclusive?: bool}
+let rangeWithOptions = (start, end, options) => {
+  let isInverted = start > end
+
+  let step = switch options.step {
+  | None => isInverted ? -1 : 1
+  | Some(0) if start !== end =>
+    Core__Error.raise(Core__Error.RangeError.make("Incorrect range arguments"))
+  | Some(n) => n
+  }
+
+  let length = if isInverted === (step >= 0) {
+    0 // infinite because step goes in opposite direction of end
+  } else if step == 0 {
+    options.inclusive === Some(true) ? 1 : 0
+  } else {
+    let range = isInverted ? start - end : end - start
+    let range = options.inclusive === Some(true) ? range + 1 : range
+    ceil(float(range) /. float(abs(step)))->Core__Float.toInt
+  }
+
+  Core__Array.fromInitializer(~length, i => start + i * step)
+}
+
+let range = (start, end) => rangeWithOptions(start, end, {})

src/Core__Int.resi

@@ -268,3 +268,57 @@ Int.mod(7, 4) == 3
 ```
 */
 external mod: (int, int) => int = "%modint"
+
+/**
+`range(start, end)` returns an int array of the sequence of integers in the
+range `[start, end)`. That is, including `start` but excluding `end`.
+
+If `start < end` the sequence will be increasing in steps of 1.
+
+If `start > end` the sequence will be decreasing in steps of -1.
+
+This is equivalent to `rangeWithOptions` with `inclusive` set to `false` and
+`step` set to `1` if `start < end` and `-1` otherwise.
+
+## Examples
+
+```rescript
+Int.range(3, 6) == [3, 4, 5]
+Int.range(-3, -1) == [-3, -2]
+Int.range(3, 1) == [3, 2]
+```
+*/
+let range: (int, int) => array<int>
+
+/**
+The options for `rangeWithOptions`.
+*/
+type rangeOptions = {step?: int, inclusive?: bool}
+
+/**
+`rangeWithOptions(start, end, options)` is like `range`, but with `step` and
+`inclusive` options configurable.
+
+If `step` is set, the sequence will increase or decrease by that amount for each
+step. If `start < end` and `step` is negative, or vice versa, an empty array is
+returned since the sequence would otherwise never reach or exceed the end value
+and hence be infinite. If `step` is `0` and `start !=` end, a `RangeError` is
+raised as the sequence would never reach or exceed the end value and hence be
+infinite.
+
+If `inclusive` is set to `true`, the sequence will include `end` if `step` is
+set such that the sequence includes it.
+
+## Examples
+
+```rescript
+Int.rangeWithOptions(3, 7, {step: 2}) == [3, 5]
+Int.rangeWithOptions(3, 7, {step: 2, inclusive: true}) == [3, 5, 7]
+Int.rangeWithOptions(3, 6, {step: -2}) // RangeError
+```
+
+## Exceptions
+
+- Raises `RangeError` if `step == 0 && start != end`.
+*/
+let rangeWithOptions: (int, int, rangeOptions) => array<int>

test/IntTests.res

@@ -0,0 +1,163 @@
+open RescriptCore
+
+let eq = (a, b) => a == b
+
+let catch = f =>
+  try {
+    let _ = f()
+    failwith("no exception raised")
+  } catch {
+  | Exn.Error(err) => err
+  }
+
+Test.run(__POS_OF__("range - positive, increasing"), Int.range(3, 6), eq, [3, 4, 5])
+Test.run(__POS_OF__("range - negative, increasing"), Int.range(-3, -1), eq, [-3, -2])
+Test.run(__POS_OF__("range - cross-zero, incresing"), Int.range(-1, 2), eq, [-1, 0, 1])
+Test.run(__POS_OF__("range - start == end"), Int.range(3, 3), eq, [])
+Test.run(__POS_OF__("range - positive, decreasing"), Int.range(3, 1), eq, [3, 2])
+Test.run(__POS_OF__("range - negative, decreasing"), Int.range(-1, -3), eq, [-1, -2])
+
+Test.run(
+  __POS_OF__("rangeWithOptions - positive, increasing, step 2"),
+  Int.rangeWithOptions(3, 6, {step: 2}),
+  eq,
+  [3, 5],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step 2"),
+  Int.rangeWithOptions(3, 7, {step: 2}),
+  eq,
+  [3, 5],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step 2"),
+  Int.rangeWithOptions(3, 8, {step: 2}),
+  eq,
+  [3, 5, 7],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions - negative, increasing, step 2"),
+  Int.rangeWithOptions(-6, -3, {step: 2}),
+  eq,
+  [-6, -4],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions - positive, increasing, step 0"),
+  catch(() => Int.rangeWithOptions(3, 6, {step: 0})),
+  eq,
+  Error.RangeError.make("Incorrect range arguments"),
+)
+Test.run(
+  __POS_OF__("rangeWithOptions - start == end, step 0"),
+  Int.rangeWithOptions(3, 3, {step: 0}),
+  eq,
+  [],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step -1"),
+  Int.rangeWithOptions(3, 6, {step: -1}),
+  eq,
+  [],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, decreasing, step 1"),
+  Int.rangeWithOptions(6, 3, {step: 1}),
+  eq,
+  [],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, decreasing, step -2"),
+  Int.rangeWithOptions(6, 3, {step: -2}),
+  eq,
+  [6, 4],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step -2"),
+  Int.rangeWithOptions(6, 2, {step: -2}),
+  eq,
+  [6, 4],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step -2"),
+  Int.rangeWithOptions(6, 1, {step: -2}),
+  eq,
+  [6, 4, 2],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + negative, decreasing, step -2"),
+  Int.rangeWithOptions(-3, -6, {step: -2}),
+  eq,
+  [-3, -5],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions - positive, increasing, step 2, inclusive"),
+  Int.rangeWithOptions(3, 6, {step: 2, inclusive: true}),
+  eq,
+  [3, 5],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step 2, inclusive"),
+  Int.rangeWithOptions(3, 7, {step: 2, inclusive: true}),
+  eq,
+  [3, 5, 7],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step 2, inclusive"),
+  Int.rangeWithOptions(3, 8, {step: 2, inclusive: true}),
+  eq,
+  [3, 5, 7],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions - negative, increasing, step 2, inclusive"),
+  Int.rangeWithOptions(-6, -3, {step: 2, inclusive: true}),
+  eq,
+  [-6, -4],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions - positive, increasing, step 0, inclusive"),
+  catch(() => Int.rangeWithOptions(3, 6, {step: 0, inclusive: true})),
+  eq,
+  Error.RangeError.make("Incorrect range arguments"),
+)
+Test.run(
+  __POS_OF__("rangeWithOptions - start == end, step 0, inclusive"),
+  Int.rangeWithOptions(3, 3, {step: 0, inclusive: true}),
+  eq,
+  [3],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step -1, inclusive"),
+  Int.rangeWithOptions(3, 6, {step: -1, inclusive: true}),
+  eq,
+  [],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, decreasing, step 1, inclusive"),
+  Int.rangeWithOptions(6, 3, {step: 1, inclusive: true}),
+  eq,
+  [],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, decreasing, step -2, inclusive"),
+  Int.rangeWithOptions(6, 3, {step: -2, inclusive: true}),
+  eq,
+  [6, 4],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step -2, inclusive"),
+  Int.rangeWithOptions(6, 2, {step: -2, inclusive: true}),
+  eq,
+  [6, 4, 2],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + positive, increasing, step -2, inclusive"),
+  Int.rangeWithOptions(6, 1, {step: -2, inclusive: true}),
+  eq,
+  [6, 4, 2],
+)
+Test.run(
+  __POS_OF__("rangeWithOptions + negative, decreasing, step -2, inclusive"),
+  Int.rangeWithOptions(-3, -6, {step: -2, inclusive: true}),
+  eq,
+  [-3, -5],
+)

test/TestSuite.mjs

@@ -1,7 +1,8 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as ErrorTests from "./ErrorTests.mjs";
+import * as IntTests from "./IntTests.mjs";
 import * as ArrayTests from "./ArrayTests.mjs";
+import * as ErrorTests from "./ErrorTests.mjs";
 import * as PromiseTest from "./PromiseTest.mjs";
 
 var TestError = PromiseTest.TestError;
@@ -22,7 +23,9 @@ var Concurrently = PromiseTest.Concurrently;
 
 var panicTest = ErrorTests.panicTest;
 
-var eq = ArrayTests.eq;
+var eq = IntTests.eq;
+
+var $$catch = IntTests.$$catch;
 
 export {
   TestError ,
@@ -35,5 +38,6 @@ export {
   Concurrently ,
   panicTest ,
   eq ,
+  $$catch ,
 }
-/* ArrayTests Not a pure module */
+/* IntTests Not a pure module */

test/TestSuite.res

@@ -1,3 +1,4 @@
 include PromiseTest
 include ErrorTests
 include ArrayTests
+include IntTests