Add lens-set-all and docs

unstable/lens/main.rkt

@@ -3,9 +3,11 @@
 (require "syntax.rkt"
          "compound.rkt"
          "list.rkt"
-         "hash.rkt")
+         "hash.rkt"
+         "view-set.rkt")
 
 (provide (all-from-out "syntax.rkt"
                        "compound.rkt"
                        "list.rkt"
-                       "hash.rkt"))
+                       "hash.rkt"
+                       "view-set.rkt"))

unstable/lens/main.scrbl

@@ -9,6 +9,7 @@ This library provides additional features for the
 may change in future releases. Do not depend on
 this library being backwards-compatible.
 
+@include-section["view-set.scrbl"]
 @include-section["compound.scrbl"]
 @include-section["list.scrbl"]
 @include-section["hash.scrbl"]

unstable/lens/view-set.rkt

@@ -0,0 +1,19 @@
+#lang racket
+
+(require lens
+         fancy-app)
+
+(module+ test
+  (require rackunit))
+
+(provide
+ (contract-out
+  [lens-set-all (->* (any/c any/c) #:rest (listof lens?) any/c)]))
+
+
+(define (lens-set-all target new-view . lenses)
+  (foldl (lens-set _ _ new-view) target lenses))
+
+(module+ test
+  (check-equal? (lens-set-all '(1 2 3 4 5) 'a first-lens third-lens fourth-lens)
+                '(a 2 a a 5)))

unstable/lens/view-set.scrbl

@@ -0,0 +1,15 @@
+#lang scribble/manual
+
+@(require lens/doc-util/main)
+
+
+@title{More Viewing and Setting}
+
+@defproc[(lens-set-all [target any/c] [new-view any/c] [lens lens?] ...) any/c]{
+  Sets the view of @racket[target] through each @racket[lens] to @racket[new--view]
+  @lenses-unstable-examples[
+    (lens-set-all '(1 2 3 4 5) 'a
+                  first-lens
+                  third-lens
+                  fourth-lens)
+]}