Add partial "mutate" implementation, failing tests

1 files changed, 36 insertions, 0 deletions

diff --git a/spellcheck/dictionary.scm b/spellcheck/dictionary.scm
new file mode 100644
index 0000000..856fec5
--- /dev/null
+++ b/spellcheck/dictionary.scm
@@ -0,0 +1,36 @@
+(define-module (dictionary)
+  #:export (create-dictionary
+            dict-occur-ref
+            dict-keys-ref
+            dict-values-ref))
+
+(define (create-dictionary lst)
+  (dictionary-helper (make-hash-table) lst))
+
+(define (dictionary-helper dict rest)
+  "Recursively adds words to DICT."
+  (if (null? rest)
+      dict
+      (begin
+        (dict-inc-word dict (car rest))
+        (dictionary-helper dict (cdr rest)))))
+
+(define (dict-inc-word dict e)
+  "Inserts word E into the DICT, using E
+as a key and the running total of occurances
+as the value."
+  (hashq-set!
+   dict e (1+ (dict-occur-ref dict e))))
+
+(define (dict-occur-ref dict e)
+  "A wrapper for hashq-ref. Returns '0' if an element
+is not present, rather than '#f'."
+  (or (hashq-ref dict e) 0))
+
+(define (dict-keys-ref dict)
+  "Returns a list of all words in the dictionary."
+  (map car (hash-map->list cons dict)))
+
+(define (dict-values-ref dict)
+  "Sums up the total number of occurances for all words."
+  (apply + (map cdr (hash-map->list cons dict))))