diff --git a/words/char-index.rkt b/words/char-index.rkt
deleted file mode 100644
index 17b0af8..0000000
--- a/words/char-index.rkt
+++ /dev/null
@@ -1,57 +0,0 @@
-#lang debug racket/base
-(require racket/file
-         racket/fasl
-         racket/vector
-         "words.rkt")
-(provide (all-defined-out))
-
-(define (char->bitindex c)
-  ;; 64-bit layout
-  ;; __________ZYXWVUTSRQPONMLKJIHGFEDCBA______zyxwvutsrqponmlkjihgfedcba
-  (cond
-    [(char<=? #\a c #\z) (- (char->integer c) 97)] ; 97 = (char->integer #\a)
-    [(char<=? #\A c #\Z) (- (char->integer c) 33)] ; 65 = (char->integer #\A)
-    [else 0]))
-
-(define (word->charidx word)
-  (apply bitwise-ior
-         (for/list ([c (in-string word)])
-           (expt 2 (char->bitindex c)))))
-
-(define (bitindex->char i)
- (cond
-   [(<= 0 i 26) (integer->char (+ i 97))]
-   [(<= 32 i 59) (integer->char (+ i 33))]
-   [else (error 'bong)]))
-
-(define (charidx->chars int)
-  (for/list ([i (in-range 64)]
-             #:when (bitwise-bit-set? int i))
-    (bitindex->char i)))
-
-(define charidx-file "compiled/charidx.rktd")
-
-(define (regenerate-char-index!)
-  (s-exp->fasl (vector-map word->charidx usable-words) (open-output-file charidx-file #:exists 'replace)))
-
-(define charidx (let ()
-                  (unless (file-exists? charidx-file)
-                    (regenerate-char-index!))
-                  (fasl->s-exp (open-input-file charidx-file))))
-
-(define (contains-char? charidx-entry c)
-  (bitwise-bit-set? charidx-entry (char->bitindex c)))
-
-(define capitalized-mask
-  (for/sum ([i (in-range 32 59)])
-    (expt 2 i)))
-
-(define (capitalized? charidx-entry)
-  ;; a cap only appears at the beginning of a word,
-  ;; so it's sufficient to test whether a cap exists in the idx
-  (positive? (bitwise-and charidx-entry capitalized-mask)))
-
-(module+ test
-  (require rackunit racket/vector)
-  (check-equal? (vector-length (vector-filter (λ (ce) (contains-char? ce #\z)) charidx)) 7830)
-  (check-equal? (charidx->chars (word->charidx "abuzz")) '(#\a #\b #\u #\z)))
diff --git a/words/index.rkt b/words/index.rkt
new file mode 100644
index 0000000..a58cdff
--- /dev/null
+++ b/words/index.rkt
@@ -0,0 +1,68 @@
+#lang debug racket/base
+(require racket/file
+         racket/fasl
+         racket/runtime-path)
+(provide (all-defined-out))
+
+(define-runtime-path wordidx-file "compiled/words/words-index.rktd")
+
+(struct word-rec (word charint length) #:prefab)
+
+(define (make-word-recs)
+  (define reverse-string (compose1 list->string reverse string->list))
+  (define omit-words (map reverse-string (file->lines "data/omit.rktd")))
+  (for/vector ([w (in-lines (open-input-file "data/words.rktd"))]
+               #:when (and (not (regexp-match "'" w)) ; no apostrophes
+                           (regexp-match #rx"^[A-Za-z]+$" w) ; no accented letters
+                           (not (member w omit-words)))) ; no bad words
+              (word-rec w
+                        (word->charidx w)
+                        (string-length w))))
+
+(define (regenerate-word-index!)
+  (make-parent-directory* wordidx-file)
+  (s-exp->fasl
+   (make-word-recs)
+   (open-output-file wordidx-file #:exists 'replace)))
+
+(define wordrecs
+  (fasl->s-exp (open-input-file (and
+                                  (unless (file-exists? wordidx-file)
+                                    (regenerate-word-index!))
+                                  wordidx-file))))
+
+(define (char->bitindex c)
+  ;; 64-bit layout
+  ;; __________ZYXWVUTSRQPONMLKJIHGFEDCBA______zyxwvutsrqponmlkjihgfedcba
+  (cond
+    [(char<=? #\a c #\z) (- (char->integer c) 97)] ; 97 = (char->integer #\a)
+    [(char<=? #\A c #\Z) (- (char->integer c) 33)] ; 65 = (char->integer #\A)
+    [else 0]))
+
+(define (word->charidx word)
+  (apply bitwise-ior
+         (for/list ([c (in-string word)])
+                   (expt 2 (char->bitindex c)))))
+
+(define (bitindex->char i)
+  (cond
+    [(<= 0 i 26) (integer->char (+ i 97))]
+    [(<= 32 i 59) (integer->char (+ i 33))]
+    [else (error 'bong)]))
+
+(define (charidx->chars int)
+  (for/list ([i (in-range 64)]
+             #:when (bitwise-bit-set? int i))
+            (bitindex->char i)))
+
+(define (contains-char? charidx-entry c)
+  (bitwise-bit-set? charidx-entry (char->bitindex c)))
+
+(define capitalized-mask
+  (for/sum ([i (in-range 32 59)])
+           (expt 2 i)))
+
+(define (capitalized? charidx-entry)
+  ;; a cap only appears at the beginning of a word,
+  ;; so it's sufficient to test whether a cap exists in the idx
+  (positive? (bitwise-and charidx-entry capitalized-mask)))
\ No newline at end of file
diff --git a/words/length-index.rkt b/words/length-index.rkt
deleted file mode 100644
index c862588..0000000
--- a/words/length-index.rkt
+++ /dev/null
@@ -1,17 +0,0 @@
-#lang debug racket/base
-(require racket/file
-         racket/fasl
-         racket/vector
-         "words.rkt")
-(provide (all-defined-out))
-
-(define lengthidx-file "compiled/lengthidx.rktd")
-
-(define (regenerate-length-index!)
-  (s-exp->fasl (vector-map string-length usable-words) (open-output-file lengthidx-file #:exists 'replace)))
-
-(define lengthidx (let ()
-                  (unless (file-exists? lengthidx-file)
-                    (regenerate-length-index!))
-                  (fasl->s-exp (open-input-file lengthidx-file))))
-
diff --git a/words/main.rkt b/words/main.rkt
index bf1151e..fe901bb 100644
--- a/words/main.rkt
+++ b/words/main.rkt
@@ -1,38 +1,48 @@
 #lang debug racket/base
 (require racket/list
          racket/file
-         "words.rkt"
-         "length-index.rkt"
-         "char-index.rkt")
+         "index.rkt")
 
-(define (wordlist #:letters [letters "etaoinshrdluw"]
-                  #:mandatory [mandatory #f]
-                  #:min [min-length 5]
-                  #:max [max-length 10]
-                  #:hide-plurals [hide-plurals? #f]
-                  #:proper-names [proper-names? #f]
-                  #:random [random #t]
-                  #:max-words [max-words 10]
-                  #:all-caps [all-caps? #f]
-                  #:initial-caps [initial-caps? #f])
+(define (make-words #:letters [letters "etaoinshrdluw"]
+                    #:mandatory [mandatory #f]
+                    #:min [min-length 5]
+                    #:max [max-length 10]
+                    #:hide-plurals [hide-plurals? #f]
+                    #:proper-names [proper-names? #f]
+                    #:random [random #t]
+                    #:max-words [max-words 10]
+                    #:all-caps [all-caps? #f]
+                    #:initial-caps [initial-caps? #f])
   (define mandatory-cs
-    (if mandatory (remove-duplicates (map char-downcase (string->list mandatory)) char=?) null))
-  (define letter-cs (remove-duplicates (append (if letters (map char-downcase (string->list letters)) null) mandatory-cs) char=?))
-  (define letter-cs-charidx (word->charidx (list->string letter-cs)))
-  (for*/fold ([ws null]
+    (if mandatory (remove-duplicates (for/list ([c (in-string mandatory)])
+                                               (char-downcase c)) char=?) null))
+  (define letter-cs-charidx
+    (word->charidx
+     (list->string
+      (remove-duplicates
+       (append (if letters
+                   (for/list ([c (in-string letters)])
+                             (char-downcase c))
+                   null)
+               mandatory-cs)
+       char=?))))
+  
+  (define capitalizer (cond
+                        [all-caps? string-upcase]
+                        [initial-caps? string-titlecase]
+                        [else values]))
+  
+  (for*/fold ([word-acc null]
               [count 0]
-              #:result (map (cond
-                              [all-caps? string-upcase]
-                              [initial-caps? string-titlecase]
-                              [else values]) ws))
-             ([idx (in-list ((if random shuffle values) (range (vector-length usable-words))))]
-              [w (in-value (vector-ref usable-words idx))]
-              [w-charidx (in-value (vector-ref charidx idx))]
-              [w-lengthidx (in-value (vector-ref lengthidx idx))]
+              #:result word-acc)
+             ([idx (in-list ((if random shuffle values) (range (vector-length wordrecs))))]
+              [rec (in-value (vector-ref wordrecs idx))]
+              [w (in-value (word-rec-word rec))]
+              [w-charidx (in-value (word-rec-charint rec))]
               #:break (= count (or max-words +inf.0))
               #:when (and
                       ;; between min and max length
-                      ((if (<= min-length max-length) <= >=) min-length w-lengthidx max-length)
+                      ((if (<= min-length max-length) <= >=) min-length (word-rec-length rec) max-length)
                       ;; word contains each mandatory char, case-insensitive
                       (or (not mandatory)
                           (for/and ([mc (in-list mandatory-cs)])
@@ -44,10 +54,10 @@
                       (if proper-names? (capitalized? w-charidx) (not (capitalized? w-charidx)))
                       ;; maybe hide plurals
                       (if hide-plurals? (not (regexp-match #rx"s$" w)) #t)))
-    (values (cons w ws) (add1 count))))
+    (values (cons (capitalizer w) word-acc) (add1 count))))
 
 (module+ test
   (require rackunit)
-  (time (wordlist))
-  (check-equal? (sort (wordlist #:mandatory "xyz") string<?)
+  (time (make-words))
+  (check-equal? (sort (make-words #:mandatory "xyz") string<?)
                 '("azoxy" "dysoxidize" "isazoxy" "oxytonize" "rhizotaxy" "zootaxy")))
\ No newline at end of file
diff --git a/words/words.rkt b/words/words.rkt
deleted file mode 100644
index f8647cf..0000000
--- a/words/words.rkt
+++ /dev/null
@@ -1,30 +0,0 @@
-#lang debug racket/base
-(require racket/file
-         racket/fasl
-         racket/string)
-(provide usable-words)
-
-(define reverse-string (compose1 list->string reverse string->list))
-
-(define omit-words (map reverse-string (file->lines "data/omit.rktd")))
-
-(define (make-wordlist)
-  ;; do global filtering here (i.e., filters that are always true)
-  (define ws
-    (for/list ([w (in-lines (open-input-file "data/words.rktd"))]
-               #:when (and (not (regexp-match "'" w)) ; no apostrophes
-                           (regexp-match #rx"^[A-Za-z]+$" w) ; no accented letters
-                           (not (member w omit-words)) ; no bad words
-                           ))
-      w))
-  ws)
-
-(define wordidx-file "compiled/wordidx.rktd")
-
-(define (regenerate-word-index!)
-  (s-exp->fasl (make-wordlist) (open-output-file wordidx-file #:exists 'replace)))
-
-(define usable-words (let ()
-                       (unless (file-exists? wordidx-file)
-                         (regenerate-word-index!))
-                       (list->vector (fasl->s-exp (open-input-file wordidx-file)))))
\ No newline at end of file