added mapBothSame and mapAllThreeSame with examples

README.md

@@ -7,10 +7,11 @@ Convenience functions for working with tuples.
 * `pairTo`, `double` and `swap` for creating and arranging tuples
 * `uncurry` and `apply` for using functions with values in a tuple
 * `maybeMapFirst` and `maybeMapSecond` for lifting a `Maybe` out of a tuple
+* `mapBothSame` for convenience to apply a function to a same-typed tuple
 
 ## `Tuple3`
 
-* Copies and extensions of all `Tuple` functions to work with 3-tuples (`first`, `second`, `third`, `mapFirst`, `mapSecond`, `mapThird`, `mapAllThree`)
+* Copies and extensions of all `Tuple` functions to work with 3-tuples (`first`, `second`, `third`, `mapFirst`, `mapSecond`, `mapThird`, `mapAllThree`, `mapAllThreeSame`)
 * Functions for creating 3-tuples (`join`, `joinTo`, `triple`, `splitFirst`, `splitSecond`)
 * Functions for rearranging values in 3-tuples (`reverse`, `rotateLeft`, `rotateRight`, `swapFirst`, `swapLast`)
 * `uncurry` and `apply` for using functions with values in a 3-tuple

src/Tuple2.elm

@@ -2,6 +2,7 @@ module Tuple2 exposing
     ( pairTo, double
     , swap
     , uncurry, apply
+    , mapBothSame
     , maybeMapFirst, maybeMapSecond
     )
 
@@ -81,6 +82,18 @@ apply : ( a -> b, a ) -> b
 apply ( fn, a ) =
     fn a
 
+{-| Apply a function to both elements of a 2-tuple where both entries are the same type.
+Convenience function to help with repetitive usage in Tuple.mapBoth()
+
+    ("1", "1000")
+        |> mapBothSame (\s -> s ++ "0")
+    --> ("10", "1000)
+
+-}
+mapBothSame : (a -> a2) -> ( a, a ) -> ( a2, a2 )
+mapBothSame fn ( a, b ) =
+    (fn a, fn b)
+
 
 {-| Apply a function that produces a `Maybe` to the first value in a 2-tuple. If
 it returns `Just something`, pair the something back with the second value in

src/Tuple3.elm

@@ -108,6 +108,17 @@ mapThird fn ( a, b, c ) =
     ( a, b, fn c )
 
 
+{-| Transform all values in a 3-Tuple. 
+
+    mapAll (List.repeat 2) ( "stressed", 16, 1 ) --> ( ["stressed", "stressed"], [16, 16], [1, 1])
+
+    mapAll String.fromInt ( 10 16 1 ) -> ( "10", "16", "1" )
+-}
+mapAll : (a -> a2) -> ( a, a, a ) -> ( a2, a2, a2)
+mapAll fn ( a, b, c ) =
+    ( fn a, fn b, fn c)
+
+
 {-| Create a 3-tuple with three values.
 
     join 1 2 3 --> ( 1, 2, 3 )