Merge pull request #194 from AlexKnauth/dict

add dict-ref-nested-lens

lens/private/dict.rkt

@@ -6,7 +6,7 @@
            (-> any/c (lens/c functional-dict? any/c))]
           ))
 
-(require racket/dict fancy-app "base/main.rkt")
+(require lens/private/util/functional-dict racket/dict fancy-app "base/main.rkt")
 (module+ test
   (require rackunit))
 
@@ -14,9 +14,6 @@
   (make-lens (dict-ref _ key)
              (dict-set _ key _)))
 
-(define (functional-dict? v)
-  (and (dict? v) (dict-can-functional-set? v)))
-
 (module+ test
   (check-equal? (lens-transform/list '((a . 1) (b . 2) (c . 3)) (dict-ref-lens 'a) (* 100 _))
                 '((a . 100) (b . 2) (c . 3))))

lens/private/util/functional-dict.rkt

@@ -0,0 +1,15 @@
+#lang sweet-exp racket/base
+
+provide functional-dict?
+
+require racket/dict
+module+ test
+  require rackunit
+
+(define (functional-dict? v)
+  (and (dict? v) (dict-can-functional-set? v)))
+
+module+ test
+  (check-true (functional-dict? (hash 'a 1 'b 2)))
+  (check-true (functional-dict? '((a . 1) (b . 2))))
+  (check-false (functional-dict? (make-hash '((a . 1) (b . 2)))))

unstable/lens/dict-nested.rkt

@@ -0,0 +1,24 @@
+#lang sweet-exp racket/base
+
+require racket/contract/base
+provide
+  contract-out
+    dict-ref-nested-lens (->* [] #:rest (listof any/c) (lens/c functional-dict? any/c))
+
+require lens/private/base/main
+        lens/private/compound/thrush
+        lens/private/dict
+        lens/private/util/functional-dict
+module+ test
+  require rackunit fancy-app
+
+(define (dict-ref-nested-lens . ks)
+  (apply lens-thrush (map dict-ref-lens ks)))
+
+module+ test
+  (define a-x (dict-ref-nested-lens 'a 'x))
+  (let-lens [val ctxt] a-x '([a . ([x . 1] [y . 2])] '[b . ([z . 3])])
+    (check-equal? val 1)
+    (check-equal? (ctxt 100) '([a . ([x . 100] [y . 2])] '[b . ([z . 3])])))
+  (check-equal? (lens-transform/list '([a . ([x . 1] [y . 2])] '[b . ([z . 3])]) a-x (* 10 _))
+                '([a . ([x . 10] [y . 2])] '[b . ([z . 3])]))

unstable/lens/dict-nested.scrbl

@@ -0,0 +1,15 @@
+#lang scribble/manual
+
+@(require lens/private/doc-util/main)
+
+@title{Lenses for nested dictionaries}
+
+@defmodule[unstable/lens/dict-nested]
+
+@defproc[(dict-ref-nested-lens [k any/c] ...) (lens/c functional-dict? any/c)]{
+Similar to @racket[hash-ref-nested-lens], but for dicts.
+@lens-unstable-examples[
+  (define a-x (dict-ref-nested-lens 'a 'x))
+  (lens-view a-x '([a . ([x . 1] [y . 2])] '[b . ([z . 3])]))
+  (lens-set a-x '([a . ([x . 1] [y . 2])] '[b . ([z . 3])]) 100)
+]}

unstable/lens/main.rkt

@@ -1,5 +1,6 @@
 #lang reprovide
 "arrow.rkt"
+"dict-nested.rkt"
 "if.rkt"
 "isomorphism.rkt"
 "mapper.rkt"

unstable/lens/main.scrbl

@@ -13,6 +13,7 @@ this library being backwards-compatible.
 
 @(include-sections
   "arrow.scrbl"
+  "dict-nested.scrbl"
   "if.scrbl"
   "isomorphism.scrbl"
   "mapper.scrbl"