From 53109568481ce082d7378c37a6e43b186be0ac3d Mon Sep 17 00:00:00 2001
From: Sam Caldwell <samc@ccs.neu.edu>
Date: Wed, 15 May 2019 17:25:11 -0400
Subject: [PATCH] more hash functions

---
 racket/typed/examples/roles/flink.rkt | 12 +++++-------
 racket/typed/hash.rkt                 | 10 ++++++++++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/racket/typed/examples/roles/flink.rkt b/racket/typed/examples/roles/flink.rkt
index b0292f1..6d44482 100644
--- a/racket/typed/examples/roles/flink.rkt
+++ b/racket/typed/examples/roles/flink.rkt
@@ -127,10 +127,10 @@ The JobManager then performs the job and, when finished, asserts (job-finished I
 (define (word-count-increment [h : WordCount]
                               [word : String]
                               -> WordCount)
-  (hash-update h
-               word
-               add1
-               #;(λ x 0)))
+  (hash-update/failure h
+                       word
+                       add1
+                       (lambda () 0)))
 
 (define (count-new-words [word-count : WordCount]
                          [words : (List String)]
@@ -168,9 +168,7 @@ The JobManager then performs the job and, when finished, asserts (job-finished I
             (define wc (count-new-words (ann (hash) WordCount) (string->words data)))
             (set! state (finished wc))]
            [(reduce-work (bind left WordCount) (bind right WordCount))
-            ;; TODO - this kind of hash-union
-            #;(define wc (hash-union left right #:combine +))
-            (define wc left)
+            (define wc (hash-union/combine left right +))
             (set! state (finished wc))])
          (set! status IDLE)]
         [#t
diff --git a/racket/typed/hash.rkt b/racket/typed/hash.rkt
index 73f9f61..86ae599 100644
--- a/racket/typed/hash.rkt
+++ b/racket/typed/hash.rkt
@@ -7,6 +7,8 @@
          hash-ref
          hash-has-key?
          hash-update
+         (typed-out [[hash-update/failure- : (∀ (K V) (→fn (Hash K V) K (→fn V V) (→fn V) (Hash K V)))]
+                     hash-update/failure])
          hash-remove
          hash-map
          hash-keys
@@ -15,6 +17,8 @@
          hash-count
          hash-empty?
          hash-union
+         (typed-out [[hash-union/combine- : (∀ (K V) (→fn (Hash K V) (Hash K V) (→fn V V V) (Hash K V)))]
+                     hash-union/combine])
          )
 
 (require "core-types.rkt")
@@ -67,3 +71,9 @@
   [hash-union : (∀ (K1 V1 K2 V2) (→fn (Hash K1 V1) (Hash K2 V2) (Hash (U K1 K2) (U V1 V2))))]
   ;; TODO - hash-union with #:combine
   )
+
+(define- (hash-update/failure- h k u err)
+  (#%app- hash-update- h k u err))
+
+(define- (hash-union/combine- h1 h2 combine)
+  (#%app- hash-union- h1 h2 #:combine combine))