Add Array.joinWith to Belt

jscomp/others/belt_Array.ml

@@ -511,3 +511,14 @@ let unzip a =
     a2.!(i) <- v2
   done;
   (a1, a2)
+
+let joinWithU a sep toString =
+  match length a with
+  | 0 -> ""
+  | l ->
+      let lastIndex = l - 1 in
+      let rec aux i res =
+        if i = lastIndex then res ^ toString a.!(i) [@bs]
+        else aux (i + 1) (res ^ toString a.!(i) [@bs] ^ sep) in
+      aux 0 ""
+let joinWith a sep toString = joinWithU a sep (fun [@bs] x -> toString x)

jscomp/others/belt_Array.mli

@@ -365,7 +365,7 @@ val map: 'a array ->  ('a -> 'b ) -> 'b array
     the beginning to end
 
     @example {[
-     map [|1;2|] (fun x-> x + 1) = [|3;4|]
+     map [|1;2|] (fun x-> x + 10) = [|11;12|]
    ]}
 
 *)
@@ -393,7 +393,7 @@ val getIndexBy: 'a array -> ('a -> bool) -> int option
 val keepU: 'a array -> ('a -> bool [@bs]) -> 'a array
 val keep: 'a array -> ('a -> bool ) -> 'a array
 (** [keep xs p ]
-    @return a new array that keep all elements satisfy [p]
+    @return a new array that keeps all elements satisfying [p]
 
     @example {[
       keep [|1;2;3|] (fun x -> x mod  2 = 0) = [|2|]
@@ -403,7 +403,9 @@ val keep: 'a array -> ('a -> bool ) -> 'a array
 val keepWithIndexU: 'a array -> ('a -> int -> bool [@bs]) -> 'a array
 val keepWithIndex: 'a array -> ('a -> int -> bool ) -> 'a array
 (** [keepWithIndex xs p ]
-    @return a new array that keep all elements satisfy [p]
+    @return a new array that keeps all elements satisfying [p]. 
+    The predicate [p] takes two arguments:
+    the element from [xs] and the index starting from 0.
 
     @example {[
       keepWithIndex [|1;2;3|] (fun _x i -> i = 1) = [|2|]
@@ -413,10 +415,10 @@ val keepWithIndex: 'a array -> ('a -> int -> bool ) -> 'a array
 val keepMapU: 'a array -> ('a -> 'b option [@bs]) -> 'b array
 val keepMap: 'a array -> ('a -> 'b option) -> 'b array
 (** [keepMap xs p]
-    @return a new array that keep all elements that return a non-None applied [p]
+    @return a new array that keeps all elements that return a non-None when applied to [p]
 
     @example {[
-      keepMap [|1;2;3|] (fun x -> if x mod 2 then Some x else None)
+      keepMap [|1;2;3|] (fun x -> if x mod 2 = 0 then Some x else None)
       = [| 2 |]
     ]}
 *)
@@ -425,16 +427,16 @@ val forEachWithIndexU: 'a array ->  (int -> 'a -> unit [@bs]) -> unit
 val forEachWithIndex: 'a array ->  (int -> 'a -> unit ) -> unit
 (** [forEachWithIndex xs f]
 
-    The same as {!forEach};except that [f] is supplied two arguments:
+    The same as {!forEach}; except that [f] is supplied with two arguments:
     the index starting from 0 and the element from [xs]
 
     @example {[
 
-      forEach [|"a";"b";"c"|] (fun i x -> Js.log("Item " ^ (string_of_int i) ^ " is " ^ x));;
+      forEachWithIndex [|"a";"b";"c"|] (fun i x -> Js.log("Item " ^ (string_of_int i) ^ " is " ^ x));;
       (*  prints:
         Item 0 is a
         Item 1 is b
-        Item 2 is cc
+        Item 2 is c
       *)
 
       let total = ref 0 ;;
@@ -522,6 +524,22 @@ val reduceWithIndex:  'a array -> 'b -> ('b -> 'a -> int -> 'b) -> 'b
     ]}
 *)
 
+val joinWithU: 'a array -> string -> ('a -> string [@bs]) -> string
+val joinWith: 'a array -> string -> ('a -> string) -> string
+(** [joinWith xs sep toString]
+
+    Concatenates all the elements of [xs] converted to string with [toString], each separated by [sep], the string 
+    given as the second argument, into a single string.
+    If the array has only one element, then that element will be returned 
+    without using the separator.
+    If the array is empty, the empty string will be returned.
+    @example{[
+      joinWith [|0; 1|] ", " string_of_int = "0, 1"
+      joinWith [||] " " string_of_int = ""
+      joinWith [|1|] " " string_of_int = "1"
+    ]}
+*)
+
 val someU: 'a array -> ('a -> bool [@bs]) -> bool
 val some: 'a array -> ('a -> bool) -> bool
 (** [some xs p]

lib/es6/belt_Array.js

@@ -652,6 +652,30 @@ function unzip(a) {
         ];
 }
 
+function joinWithU(a, sep, toString) {
+  var l = a.length;
+  if (l === 0) {
+    return "";
+  }
+  var lastIndex = l - 1 | 0;
+  var _i = 0;
+  var _res = "";
+  while(true) {
+    var res = _res;
+    var i = _i;
+    if (i === lastIndex) {
+      return res + toString(a[i]);
+    }
+    _res = res + (toString(a[i]) + sep);
+    _i = i + 1 | 0;
+    continue ;
+  };
+}
+
+function joinWith(a, sep, toString) {
+  return joinWithU(a, sep, Curry.__1(toString));
+}
+
 export {
   get ,
   getExn ,
@@ -707,6 +731,8 @@ export {
   reduceReverse2 ,
   reduceWithIndexU ,
   reduceWithIndex ,
+  joinWithU ,
+  joinWith ,
   someU ,
   some ,
   everyU ,

lib/js/belt_Array.js

@@ -652,6 +652,30 @@ function unzip(a) {
         ];
 }
 
+function joinWithU(a, sep, toString) {
+  var l = a.length;
+  if (l === 0) {
+    return "";
+  }
+  var lastIndex = l - 1 | 0;
+  var _i = 0;
+  var _res = "";
+  while(true) {
+    var res = _res;
+    var i = _i;
+    if (i === lastIndex) {
+      return res + toString(a[i]);
+    }
+    _res = res + (toString(a[i]) + sep);
+    _i = i + 1 | 0;
+    continue ;
+  };
+}
+
+function joinWith(a, sep, toString) {
+  return joinWithU(a, sep, Curry.__1(toString));
+}
+
 exports.get = get;
 exports.getExn = getExn;
 exports.set = set;
@@ -706,6 +730,8 @@ exports.reduceReverse2U = reduceReverse2U;
 exports.reduceReverse2 = reduceReverse2;
 exports.reduceWithIndexU = reduceWithIndexU;
 exports.reduceWithIndex = reduceWithIndex;
+exports.joinWithU = joinWithU;
+exports.joinWith = joinWith;
 exports.someU = someU;
 exports.some = some;
 exports.everyU = everyU;