+ map3Shortest and zip3shortest to Array and ResizeArray

Author: gusty

src/FSharpPlus/Extensions/Array.fs

@@ -238,6 +238,15 @@ module Array =
 
         Array.init (min a1.Length a2.Length) (fun i -> f a1.[i] a2.[i])
 
+    /// <summary>Safely build a new array whose elements are the results of applying the given function
+    /// to each of the elements of the three arrays pairwise.</summary>
+    /// <remark>If one array is shorter, excess elements are discarded from the right end of the longer array.</remark>
+    let map3Shortest f (a1: 'T1 []) (a2: 'T2 []) (a3: 'T3 []) =
+        raiseIfNull (nameof a1) a1
+        raiseIfNull (nameof a2) a2
+        raiseIfNull (nameof a3) a3
+        Array.init (min a1.Length a2.Length |> min a3.Length) (fun i -> f a1.[i] a2.[i] a3.[i])
+    
     /// <summary>
     /// Zip safely two arrays. If one array is shorter, excess elements are discarded from the right end of the longer array. 
     /// </summary>
@@ -250,6 +259,19 @@ module Array =
 
         Array.init (min a1.Length a2.Length) (fun i -> a1.[i], a2.[i])
 
+    /// <summary>
+    /// Zip safely three arrays. If one array is shorter, excess elements are discarded from the right end of the longer array. 
+    /// </summary>
+    /// <param name="a1">First input array.</param>
+    /// <param name="a2">Second input array.</param>
+    /// <param name="a3">Third input array.</param>
+    /// <returns>Array with corresponding tuple of input arrays.</returns>
+    let zip3Shortest (a1: array<'T1>) (a2: array<'T2>) (a3: array<'T3>) =
+        raiseIfNull (nameof a1) a1
+        raiseIfNull (nameof a2) a2
+        raiseIfNull (nameof a3) a3
+        Array.init (min a1.Length a2.Length |> min a3.Length) (fun i -> a1.[i], a2.[i], a3.[i])
+
     /// <summary>Same as choose but with access to the index.</summary>
     /// <param name="mapping">The mapping function, taking index and element as parameters.</param>
     /// <param name="source">The input array.</param>

src/FSharpPlus/Extensions/ResizeArray.fs

@@ -134,6 +134,16 @@ module ResizeArray =
             ra.Add (f a1.[i] a2.[i])
         ra
 
+    /// <summary>Safely build a new ResizeArray whose elements are the results of applying the given function
+    /// to each of the elements of the three ResizeArrays pairwise.</summary>
+    /// <remark>If one array is shorter, excess elements are discarded from the right end of the longer array.</remark>
+    let map3Shortest f (a1: ResizeArray<'T1>) (a2: ResizeArray<'T2>) (a3: ResizeArray<'T3>) =
+        let len = min a1.Count a2.Count |> min a3.Count
+        let ra = ResizeArray len
+        for i in 0..(len-1) do
+            ra.Add (f a1.[i] a2.[i] a3.[i])
+        ra
+    
     /// <summary>
     /// Zip safely two ResizeArrays. If one ResizeArray is shorter, excess elements are discarded from the right end of the longer ResizeArray. 
     /// </summary>
@@ -146,3 +156,17 @@ module ResizeArray =
         for i in 0..(len-1) do
             ra.Add (a1.[i], a2.[i])
         ra
+
+    /// <summary>
+    /// Zip safely three ResizeArrays. If one ResizeArray is shorter, excess elements are discarded from the right end of the longer ResizeArray.
+    /// </summary>
+    /// <param name="a1">First input ResizeArray.</param>
+    /// <param name="a2">Second input ResizeArray.</param>
+    /// <param name="a3">Third input ResizeArray.</param>
+    /// <returns>ResizeArray with corresponding pairs of input ResizeArrays.</returns>
+    let zip3Shortest (a1: ResizeArray<'T1>) (a2: ResizeArray<'T2>) (a3: ResizeArray<'T3>) =
+        let len = min a1.Count a2.Count |> min a3.Count
+        let ra = ResizeArray len
+        for i in 0..(len-1) do
+            ra.Add (a1.[i], a2.[i], a3.[i])
+        ra