Nullable additions (#67)

* feat(nullable): add getExn

* feat(nullable): add getUnsafe

* feat(nullable): add getWithDefault

* feat(nullable): add map

* feat(nullable): add mapWithDefault

* feat(nullable): add flatMap

* docs(nullable): add interface

* docs(changelog): add changelog entry for Nullable additions

* docs(nullable): fix typo x -> value

Co-authored-by: Pedro Castro <[email protected]>

* feat(nullable/map+flatMap): return value unchanged if null or undefined

---------

Co-authored-by: Pedro Castro <[email protected]>

Author: glennsl

CHANGELOG.md

@@ -17,6 +17,7 @@
 - Remove `Date.valueOf` as it returns the same as `Date.getTime`. https://github.com/rescript-association/rescript-core/pull/61
 - Change `Float.fromString` signature. Now accepts only string. https://github.com/rescript-association/rescript-core/pull/54
 - Change `Float.parseFloat` signature. Now accepts only string. https://github.com/rescript-association/rescript-core/pull/54
+- Add `getExn`, `getUnsafe`, `getWithDefault`, `map`, `mapWithDefault` and `flatMap` to `Nullable`. https://github.com/rescript-association/rescript-core/pull/67
 
 ### Documentation
 

src/Core__Nullable.mjs

@@ -1,5 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
+import * as Curry from "rescript/lib/es6/curry.js";
 import * as Caml_option from "rescript/lib/es6/caml_option.js";
 
 function fromOption(option) {
@@ -9,7 +10,55 @@ function fromOption(option) {
 
 }
 
+function getWithDefault(value, $$default) {
+  if (value == null) {
+    return $$default;
+  } else {
+    return value;
+  }
+}
+
+function getExn(value) {
+  if (!(value == null)) {
+    return value;
+  }
+  throw {
+        RE_EXN_ID: "Invalid_argument",
+        _1: "Nullable.getExn: value is null or undefined",
+        Error: new Error()
+      };
+}
+
+function map(value, f) {
+  if (value == null) {
+    return value;
+  } else {
+    return Curry._1(f, value);
+  }
+}
+
+function mapWithDefault(value, $$default, f) {
+  if (value == null) {
+    return $$default;
+  } else {
+    return Curry._1(f, value);
+  }
+}
+
+function flatMap(value, f) {
+  if (value == null) {
+    return value;
+  } else {
+    return Curry._1(f, value);
+  }
+}
+
 export {
   fromOption ,
+  getWithDefault ,
+  getExn ,
+  map ,
+  mapWithDefault ,
+  flatMap ,
 }
 /* No side effect */

src/Core__Nullable.res

@@ -13,3 +13,35 @@ let fromOption: option<'a> => t<'a> = option =>
   | Some(x) => make(x)
   | None => undefined
   }
+
+let getWithDefault = (value, default) =>
+  switch value->toOption {
+  | Some(x) => x
+  | None => default
+  }
+
+let getExn: t<'a> => 'a = value =>
+  switch value->toOption {
+  | Some(x) => x
+  | None => raise(Invalid_argument("Nullable.getExn: value is null or undefined"))
+  }
+
+external getUnsafe: t<'a> => 'a = "%identity"
+
+let map = (value, f) =>
+  switch value->toOption {
+  | Some(x) => make(f(x))
+  | None => Obj.magic(value)
+  }
+
+let mapWithDefault = (value, default, f) =>
+  switch value->toOption {
+  | Some(x) => f(x)
+  | None => default
+  }
+
+let flatMap = (value, f) =>
+  switch value->toOption {
+  | Some(x) => f(x)
+  | None => Obj.magic(value)
+  }

src/Core__Nullable.resi

@@ -81,3 +81,102 @@ let asNullable = optString->Nullable.fromOption // Nullable.t<string>
 ```
 */
 let fromOption: option<'a> => t<'a>
+
+/**
+`getWithDefault(value, default)` returns `value` if not `null` or `undefined`,
+otherwise return `default`.
+
+## Examples
+
+```rescript
+Nullable.getWithDefault(Nullable.null, "Banana") // Banana
+Nullable.getWithDefault(Nulalble.make("Apple"), "Banana") // Apple
+
+let greet = (firstName: option<string>) =>
+  "Greetings " ++ firstName->Nullable.getWithDefault("Anonymous")
+
+Nullable.make("Jane")->greet // "Greetings Jane"
+Nullable.null->greet // "Greetings Anonymous"
+```
+*/
+let getWithDefault: (t<'a>, 'a) => 'a
+
+/**
+`getExn(value)` raises an exception if `null` or `undefined`, otherwise returns the value.
+
+```rescript
+Nullable.getExn(Nullable.make(3)) // 3
+Nullable.getExn(Nullable.null) /* Raises an Error */
+```
+
+## Exceptions
+
+- Raises `Invalid_argument` if `value` is `null` or `undefined`
+*/
+let getExn: t<'a> => 'a
+
+/**
+`getUnsafe(value)` returns `value`.
+
+## Examples
+
+```rescript
+Nullable.getUnsafe(Nullable.make(3)) == 3
+Nullable.getUnsafe(Nullable.null) // Raises an error
+```
+
+## Important
+
+- This is an unsafe operation, it assumes `value` is not `null` or `undefined`.
+*/
+external getUnsafe: t<'a> => 'a = "%identity"
+
+/**
+`map(value, f)` returns `f(value)` if `value` is not `null` or `undefined`,
+otherwise returns `value` unchanged.
+
+## Examples
+
+```rescript
+Nullable.map(Nullable.make(3), x => x * x) // Nullable.make(9)
+Nullable.map(Nullable.undefined, x => x * x) // Nullable.undefined
+```
+*/
+let map: (t<'a>, 'a => 'b) => t<'b>
+
+/**
+`mapWithDefault(value, default, f)` returns `f(value)` if `value` is not `null`
+or `undefined`, otherwise returns `default`.
+
+## Examples
+
+```rescript
+let someValue = Nullable.make(3)
+someValue->Nullable.mapWithDefault(0, x => x + 5) // 8
+
+let noneValue = Nullable.null
+noneValue->Nullable.mapWithDefault(0, x => x + 5) // 0
+```
+*/
+let mapWithDefault: (t<'a>, 'b, 'a => 'b) => 'b
+
+/**
+`flatMap(value, f)` returns `f(value)` if `value` is not `null` or `undefined`,
+otherwise returns `value` unchanged.
+
+## Examples
+
+```rescript
+let addIfAboveOne = value =>
+  if (value > 1) {
+    Nullable.make(value + 1)
+  } else {
+    Nullable.null
+  }
+
+Nullable.flatMap(Nullable.make(2), addIfAboveOne) // Nullable.make(3)
+Nullable.flatMap(Nullable.make(-4), addIfAboveOne) // Nullable.undefined
+Nullable.flatMap(Nullable.null, addIfAboveOne) // Nullable.undefined
+```
+*/
+let flatMap: (t<'a>, 'a => t<'b>) => t<'b>