Add option module to belt

Author: arnarthor

Diff for: jscomp/others/Makefile

@@ -34,6 +34,7 @@ SOURCE_LIST= node_path node_fs node_process dict node_module js_array js_string
 	belt_internalMapString\
 	belt_MapString \
 	belt_MapInt\
+  belt_Option\
 	belt_internalSet\
 	belt_Set\
 	belt_MutableSet\

Diff for: jscomp/others/belt.ml

@@ -232,7 +232,11 @@ module HashSet = Belt_HashSet
 *)
 module HashMap = Belt_HashMap
 
+(** {!Belt.Option}
 
+    Utilities for option data type
+*)
 
+module Option = Belt_Option
 
 

Diff for: jscomp/others/belt_Option.ml

@@ -0,0 +1,27 @@
+let getExn = function
+  | Some x -> x
+  | None -> assert false
+
+let fold opt default f = match opt with
+  | Some x -> f x
+  | None -> default
+
+let map opt f = match opt with
+  | Some x -> Some (f x)
+  | None -> None
+
+let flatMap opt f = match opt with
+  | Some x -> f x
+  | None -> None
+
+let getOrElse opt default = match opt with
+  | Some x -> x
+  | None -> default
+
+let exists = function
+  | Some _ -> true
+  | None -> false
+
+let empty = function
+  | Some _ -> false
+  | None -> true

Diff for: jscomp/others/belt_Option.mli

@@ -0,0 +1,7 @@
+val getExn : 'a option -> 'a
+val fold : 'a option -> 'b -> ('a -> 'b) -> 'b
+val map : 'a option -> ('a -> 'b) -> 'b option
+val flatMap : 'a option -> ('a -> 'b option) -> 'b option
+val getOrElse : 'a option -> 'a -> 'a
+val exists : 'a option -> bool
+val empty : 'a option -> bool

Diff for: lib/js/belt.js

@@ -27,6 +27,8 @@ var HashSet = 0;
 
 var HashMap = 0;
 
+var Option = 0;
+
 exports.Id = Id;
 exports.$$Array = $$Array;
 exports.SortArray = SortArray;
@@ -40,4 +42,5 @@ exports.MutableSet = MutableSet;
 exports.MutableMap = MutableMap;
 exports.HashSet = HashSet;
 exports.HashMap = HashMap;
+exports.Option = Option;
 /* No side effect */

Diff for: lib/js/belt_Option.js

@@ -0,0 +1,68 @@
+'use strict';
+
+var Curry = require("./curry.js");
+
+function getExn(param) {
+  if (param) {
+    return param[0];
+  } else {
+    return /* assert false */0;
+  }
+}
+
+function fold(opt, $$default, f) {
+  if (opt) {
+    return Curry._1(f, opt[0]);
+  } else {
+    return $$default;
+  }
+}
+
+function map(opt, f) {
+  if (opt) {
+    return /* Some */[Curry._1(f, opt[0])];
+  } else {
+    return /* None */0;
+  }
+}
+
+function flatMap(opt, f) {
+  if (opt) {
+    return Curry._1(f, opt[0]);
+  } else {
+    return /* None */0;
+  }
+}
+
+function getOrElse(opt, $$default) {
+  if (opt) {
+    return opt[0];
+  } else {
+    return $$default;
+  }
+}
+
+function exists(param) {
+  if (param) {
+    return /* true */1;
+  } else {
+    return /* false */0;
+  }
+}
+
+function empty(param) {
+  if (param) {
+    return /* false */0;
+  } else {
+    return /* true */1;
+  }
+}
+
+exports.getExn = getExn;
+exports.fold = fold;
+exports.map = map;
+exports.flatMap = flatMap;
+exports.getOrElse = getOrElse;
+exports.exists = exists;
+exports.empty = empty;
+/* No side effect */