Add dict library

1 files changed, 50 insertions, 0 deletions

diff --git a/dict.scm b/dict.scm
new file mode 100644
index 0000000..564b1ae
--- /dev/null
+++ b/dict.scm
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+#!r6rs
+;; Experimental python-like dictionary.  Import this qualified, eg:
+;;     (import (prefix (dict) dict/))
+;; or
+;;     (import (prefix (dict) dict.))
+(library (dict (2))
+  (export
+   empty new dict dict? keys vals contains?
+   set get del update map)
+  (import
+    (rnrs base)
+    (srfi srfi-69))
+
+  (define (empty)
+    (make-hash-table))
+
+  (define (new tuples)
+    (let ([dict (make-hash-table)])
+      (map (lambda (k . v) (hash-table-set! dict k v)) tuples)
+      dict))
+
+  (define (dict? dict)
+    (hash-table? dict))
+
+  (define (keys dict)
+    (hash-table-keys dict))
+
+  (define (vals dict)
+    (hash-table-values dict))
+
+  (define (len dict)
+    (hash-table-size dict))
+
+  (define (contains? dict key)
+    (hash-table-exists? dict key))
+
+  (define (set dict key value)
+    (hash-table-set! dict key value))
+
+  (define (get dict key)
+    (hash-table-ref dict key #f))
+
+  (define (del dict key)
+    (hash-table-delete! dict key))
+
+  (define (update dict key func)
+    (hash-table-update! dict key func (lambda () '())))
+
+  (define (map func dict)
+    (hash-table-walk dict func)))