From 86e584b983eba1ba2ce42f411e1f441003392f97 Mon Sep 17 00:00:00 2001
From: Danny Yoo <dyoo@cs.wpi.edu>
Date: Wed, 9 Nov 2011 11:31:19 -0500
Subject: [PATCH] hash-map and hash-for-each

---
 lang/base.rkt         |  2 ++
 lang/private/hash.rkt | 29 +++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 lang/private/hash.rkt

diff --git a/lang/base.rkt b/lang/base.rkt
index 5243933..b76b471 100644
--- a/lang/base.rkt
+++ b/lang/base.rkt
@@ -14,10 +14,12 @@
          (all-from-out "private/list.rkt")
          (all-from-out "list.rkt")
          (all-from-out "private/map.rkt")
+         (all-from-out "private/hash.rkt")
          quasiquote)
          
 (require "private/list.rkt"
          "private/map.rkt"
+         "private/hash.rkt"
          "list.rkt"
          (only-in "private/qq-and-or.rkt" quasiquote))
 
diff --git a/lang/private/hash.rkt b/lang/private/hash.rkt
new file mode 100644
index 0000000..b41864e
--- /dev/null
+++ b/lang/private/hash.rkt
@@ -0,0 +1,29 @@
+#lang s-exp "../kernel.rkt"
+
+(provide hash-map hash-for-each)
+
+(define (hash-map a-hash f)
+  (unless (hash? a-hash)
+    (raise-type-error 'hash-map "hash" a-hash))
+  (unless (and (procedure? f) (procedure-arity-includes? f 2))
+    (raise-type-error 'hash-map "procedure (arity 2)" f))
+  (let loop ([keys (hash-keys a-hash)])
+    (if (null? keys)
+        '()
+        (cons (f (car keys) (hash-ref a-hash (car keys)))
+              (loop (rest keys))))))
+
+
+(define (hash-for-each a-hash f)
+  (unless (hash? a-hash)
+    (raise-type-error 'hash-for-each "hash" a-hash))
+  (unless (and (procedure? f) (procedure-arity-includes? f 2))
+    (raise-type-error 'hash-for-each "procedure (arity 2)" f))
+  (let loop ([keys (hash-keys a-hash)])
+    (if (null? keys)
+        (void)
+        (begin
+          (f (car keys) (hash-ref a-hash (car keys)))
+          (loop (rest keys))))))
+
+