diff --git a/lib/chibi/char-set.sld b/lib/chibi/char-set.sld
index 12598914..c3cf75c0 100644
--- a/lib/chibi/char-set.sld
+++ b/lib/chibi/char-set.sld
@@ -1,4 +1,6 @@
 
+;;> A minimal character set library.
+
 (define-library (chibi char-set)
   (import (chibi char-set base) (chibi char-set extras))
   (export
diff --git a/lib/chibi/crypto/md5.scm b/lib/chibi/crypto/md5.scm
index 36e969b8..3858eb06 100644
--- a/lib/chibi/crypto/md5.scm
+++ b/lib/chibi/crypto/md5.scm
@@ -130,6 +130,10 @@
      #xffef #xf47d #x8584 #x5dd1 #x6fa8 #x7e4f #xfe2c #xe6e0 #xa301 #x4314
      #x4e08 #x11a1 #xf753 #x7e82 #xbd3a #xf235 #x2ad7 #xd2bb #xeb86 #xd391))
 
+;;> Returns the md5 checksum of \var{src} as a lowercase hex-string.
+;;> \var{src} can be any of a string (interpreted as utf8), a
+;;> bytevector, or a binary input port.
+
 (define (md5 src)
   (let ((in (cond ((string? src) (open-input-bytevector (string->utf8 src)))
                   ((bytevector? src) (open-input-bytevector src))
diff --git a/lib/chibi/crypto/md5.sld b/lib/chibi/crypto/md5.sld
index 47872136..69caeb6e 100644
--- a/lib/chibi/crypto/md5.sld
+++ b/lib/chibi/crypto/md5.sld
@@ -1,4 +1,7 @@
 
+;;> Implementation of the MD5 (Message Digest) cryptographic hash.  In
+;;> new applications SHA-2 should be preferred.
+
 (define-library (chibi crypto md5)
   (import (scheme base) (chibi bytevector))
   (cond-expand
diff --git a/lib/chibi/crypto/rsa.sld b/lib/chibi/crypto/rsa.sld
index d3f1a99c..37a10663 100644
--- a/lib/chibi/crypto/rsa.sld
+++ b/lib/chibi/crypto/rsa.sld
@@ -1,4 +1,6 @@
 
+;;> RSA public key cryptography implementation.
+
 (define-library (chibi crypto rsa)
   (import (scheme base) (srfi 27)
           (chibi bytevector) (chibi math prime))
diff --git a/lib/chibi/crypto/sha2.sld b/lib/chibi/crypto/sha2.sld
index a08c09a7..5282a1b2 100644
--- a/lib/chibi/crypto/sha2.sld
+++ b/lib/chibi/crypto/sha2.sld
@@ -1,4 +1,7 @@
 
+;;> Implementation of the SHA-2 (Secure Hash Algorithm) cryptographic
+;;> hash.
+
 (define-library (chibi crypto sha2)
   (import (scheme base))
   (export sha-224 sha-256)
diff --git a/lib/chibi/iset.sld b/lib/chibi/iset.sld
index 9ea3e6d5..7ecb0c13 100644
--- a/lib/chibi/iset.sld
+++ b/lib/chibi/iset.sld
@@ -1,66 +1,10 @@
-;; base.scm - base integer set operations
-;; Copyright (c) 2004-2012 Alex Shinn. All rights reserved.
+;; Copyright (c) 2004-2015 Alex Shinn. All rights reserved.
 ;; BSD-style license: http://synthcode.com/license.txt
 
-;; An integer set (iset) is a set of exact integers optimized for
-;; minimal space usage and fast membership lookup.  General set
-;; operations are provided based on the character set operations found
-;; in SRFI-14.
-;;
-;; Creating isets:
-;;
-;; (make-iset)     ; an empty integer set
-;; (make-iset n)   ; a set of the single integer N
-;; (make-iset n m) ; a set of the range of all integers from N-M inclusive
-;;
-;; The following procedures are provided as direct analogs of the
-;; SRFI-14 procedures, accepting and returning isets and integers in
-;; place of char-sets and characters:
-;;
-;; Creating isets:
-;;
-;; (iset-copy is)            ; a new copy of IS
-;; (iset n ...)              ; an iset containing the elements N...
-;; (list->iset ls [base-is]) ; an iset containing all the integers in
-;;                           ; list LS, union BASE-IS if provided
-;; (list->iset! ls base-is)  ; same as above, allowed but not required to
-;;                           ; modify base-is
-;;
-;; Querying isets:
-;;
-;; (iset-size is)          ; return the # of elements in IS
-;; (iset-contains? is n)   ; test N for membership in IS
-;; (iset->list is)         ; returns a list of all integers in IS
-;;
-;; Predicates:
-;;
-;; (iset? obj)     ; #t iff obj is an integer set
-;; (iset= is ...)  ; #t iff all arguments are equivalent integer sets
-;; (iset<= is ...) ; #t iff the arguments are monotonically increasing sets
-;; (iset>= is ...) ; #t iff the arguments are monotonically decreasing sets
-;;
-;; Cursors:
-;;
-;; (iset-cursor iset)
-;; (iset-ref iset cursor)
-;; (iset-cursor-next iset cursor)
-;; (end-of-iset? iset)
-;;
-;; Set operations:
-;;
-;; (iset-adjoin is n ...)         ; char-set-adjoin
-;; (iset-delete is n ...)         ; char-set-delete
-;;
-;; (iset-adjoin! is n ...)        ; char-set-adjoin!
-;; (iset-delete! is n ...)        ; char-set-delete!
-;;
-;; (iset-union is1 ...)                  ; char-set-union
-;; (iset-intersection is1 ...)           ; char-set-intersection
-;; (iset-difference is1 is2 ...)         ; char-set-difference
-;;
-;; (iset-union! is1 ...)                 ; char-set-union!
-;; (iset-intersection! is1 ...)          ; char-set-intersection!
-;; (iset-difference! is1 is2 ...)        ; char-set-difference!
+;;> A space efficient integer set (iset) implementation, optimized for
+;;> minimal space usage and fast membership lookup.  General set
+;;> operations are provided based on the character set operations
+;;> found in SRFI-14.
 
 (define-library (chibi iset)
   (import (chibi iset base)
diff --git a/lib/chibi/iset/base.scm b/lib/chibi/iset/base.scm
index 5f917ddc..cf3f58a9 100644
--- a/lib/chibi/iset/base.scm
+++ b/lib/chibi/iset/base.scm
@@ -13,12 +13,20 @@
   (left  iset-left  iset-left-set!)
   (right iset-right iset-right-set!))
 
+;;> Create a new iset.  Takes two optional arguments, \var{n} and
+;;> \var{m}.  If only \var{n} is provided the set contains only a
+;;> single element.  If \var{m} is provided the set contains all
+;;> integers from \var{n} to \var{m} inclusive.  If neither is
+;;> provided the set is initially empty.
+
 (define (make-iset . opt)
   (if (null? opt)
       (%make-iset 0 0 0 #f #f)
       (let ((end (if (pair? (cdr opt)) (cadr opt) (car opt))))
         (%make-iset (car opt) end #f #f #f))))
 
+;;> Returns true iff \var{iset} contains the integer \var{n}.
+
 (define (iset-contains? iset n)
   (let lp ((is iset))
     (let ((start (iset-start is)))
diff --git a/lib/chibi/iset/constructors.scm b/lib/chibi/iset/constructors.scm
index 6c09d553..c9bd336e 100644
--- a/lib/chibi/iset/constructors.scm
+++ b/lib/chibi/iset/constructors.scm
@@ -13,16 +13,27 @@
       (- n (arithmetic-shift 1 index))
       n))
 
+;;> Create a new iset composed of each of the integers in \var{args}.
+
 (define (iset . args)
   (list->iset args))
 
+;;> Returns an iset with all integers in the list \var{ls} added to
+;;> \var{iset}, possibly mutating \var{iset} in the process.
+
 (define (list->iset! ls iset)
   (for-each (lambda (i) (iset-adjoin1! iset i)) ls)
   iset)
 
+;;> Returns an iset with all integers in the list \var{ls}.  If the
+;;> optional argument \var{iset} is provided, also includes all
+;;> elements in \var{iset}, leaving \var{iset} unchanged.
+
 (define (list->iset ls . opt)
   (list->iset! ls (if (pair? opt) (iset-copy (car opt)) (make-iset))))
 
+;;> Returns a new copy of \var{iset}.
+
 (define (iset-copy iset)
   (and iset
        (%make-iset
@@ -185,9 +196,15 @@
                 (min end (iset-end node))
                 #f #f #f))))
 
+;;> Returns an iset with the integers in \var{ls} added to \var{iset},
+;;> possibly mutating \var{iset} in the process.
+
 (define (iset-adjoin! iset . ls)
   (list->iset! ls iset))
 
+;;> Returns an iset with the integers in \var{ls} added to \var{iset},
+;;> without changing \var{iset}.
+
 (define (iset-adjoin iset . ls)
   (list->iset ls iset))
 
@@ -221,13 +238,22 @@
                   (if right (lp right)))
                 (%iset-delete1! is n)))))))
 
+;;> Returns an iset with the integers in \var{ls} removed (if present)
+;;> from \var{iset}, possibly mutating \var{iset} in the process.
+
 (define (iset-delete! iset . args)
   (for-each (lambda (i) (iset-delete1! iset i)) args)
   iset)
 
+;;> Returns an iset with the integers in \var{ls} removed (if present)
+;;> from \var{iset}, without changing \var{iset}.
+
 (define (iset-delete iset . args)
   (apply iset-delete! (iset-copy iset) args))
 
+;;> Returns an iset composed of the integers resulting from applying
+;;> \var{proc} to every element of \var{iset}.
+
 (define (iset-map proc iset)
   (iset-fold (lambda (i is) (iset-adjoin! is (proc i))) (make-iset) iset))
 
@@ -255,6 +281,10 @@
      (a a)
      (else (make-iset)))))
 
+;;> Returns an iset containing all integers which occur in any of the
+;;> isets \var{args}.  If no \var{args} are present returns an empty
+;;> iset.
+
 (define (iset-union . args)
   (if (null? args)
     (make-iset)
@@ -270,9 +300,17 @@
       (apply iset-intersection! a (cdr args)))
      (else a))))
 
+;;> Returns an iset containing all integers which occur in \var{a} and
+;;> every of the isets \var{args}.  If no \var{args} are present
+;;> returns \var{a}.
+
 (define (iset-intersection a . args)
   (apply iset-intersection! (iset-copy a) args))
 
+;;> Returns an iset containing all integers which occur in \var{a},
+;;> but removing those which occur in any of the isets \var{args}.  If
+;;> no \var{args} are present returns \var{a}.  May mutate \var{a}.
+
 (define (iset-difference! a . args)
   (if (null? args)
       a
@@ -280,5 +318,7 @@
         (iset-for-each (lambda (i) (iset-delete1! a i)) (car args))
         (apply iset-difference! a (cdr args)))))
 
+;;> As above but doesn't change \var{a}.
+
 (define (iset-difference a . args)
   (apply iset-difference! (iset-copy a) args))
diff --git a/lib/chibi/iset/iterators.scm b/lib/chibi/iset/iterators.scm
index 2814a969..bd43f99c 100644
--- a/lib/chibi/iset/iterators.scm
+++ b/lib/chibi/iset/iterators.scm
@@ -2,6 +2,8 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Cursors
 
+;;> Returns true iff \var{iset} is empty.
+
 (define (iset-empty? iset)
   (and (iset? iset)
        (cond ((iset-bits iset) => zero?) (else #f))
@@ -15,14 +17,15 @@
   (pos iset-cursor-pos iset-cursor-pos-set!)
   (stack iset-cursor-stack iset-cursor-stack-set!))
 
-;; Create a new iset cursor pointing to the first element of iset,
-;; with an optional stack argument.
 (define (%iset-cursor iset . o)
   (iset-cursor-advance
    (make-iset-cursor iset
                      (or (iset-bits iset) (iset-start iset))
                      (if (pair? o) (car o) '()))))
 
+;;> Create a new iset cursor pointing to the first element of iset,
+;;> with an optional stack argument.
+
 (define (iset-cursor iset . o)
   (let ((stack (if (pair? o) (car o) '())))
     (if (iset-left iset)
@@ -51,6 +54,10 @@
       (iset-cursor-pop cur))
      (else cur))))
 
+;;> Return a new iset cursor pointing to the next element of
+;;> \var{iset} after \var{cur}.  If \var{cur} is already at
+;;> \scheme{end-of-iset?}, the resulting cursor is as well.
+
 (define (iset-cursor-next iset cur)
   (iset-cursor-advance
    (let ((node (iset-cursor-node cur))
@@ -59,6 +66,9 @@
      (let ((pos (if (iset-bits node) (bitwise-and pos (- pos 1)) (+ pos 1))))
        (make-iset-cursor node pos stack)))))
 
+;;> Return the element of iset \var{iset} at cursor \var{cur}.  If the
+;;> cursor is at \scheme{end-of-iset?}, raises an error.
+
 (define (iset-ref iset cur)
   (let ((node (iset-cursor-node cur))
         (pos (iset-cursor-pos cur)))
@@ -74,7 +84,10 @@
           (error "cursor reference past end of iset")
           pos)))))
 
-(define (end-of-iset? cur)
+;;> Returns true iff \var{cur} is at the end of \var{iset}, such that
+;;> \scheme{iset-ref} is no longer valid.
+
+(define (end-of-iset? iset cur)
   (let ((node (iset-cursor-node cur)))
     (and (if (iset-bits node)
              (zero? (iset-cursor-pos cur))
@@ -88,8 +101,8 @@
 (define (iset2= is1 is2)
   (let lp ((cur1 (iset-cursor is1))
            (cur2 (iset-cursor is2)))
-    (cond ((end-of-iset? cur1) (end-of-iset? cur2))
-          ((end-of-iset? cur2) #f)
+    (cond ((end-of-iset? is1 cur1) (end-of-iset? is2 cur2))
+          ((end-of-iset? is2 cur2) #f)
           ((= (iset-ref is1 cur1) (iset-ref is2 cur2))
            (lp (iset-cursor-next is1 cur1) (iset-cursor-next is2 cur2)))
           (else
@@ -98,8 +111,8 @@
 (define (iset2<= is1 is2)
   (let lp ((cur1 (iset-cursor is1))
            (cur2 (iset-cursor is2)))
-    (cond ((end-of-iset? cur1))
-          ((end-of-iset? cur2) #f)
+    (cond ((end-of-iset? is1 cur1))
+          ((end-of-iset? is2 cur2) #f)
           (else
            (let ((i1 (iset-ref is1 cur1))
                  (i2 (iset-ref is1 cur2)))
@@ -112,16 +125,29 @@
                     ;; (< i1 i2) - i1 won't occur in is2
                     #f)))))))
 
+;;> Returns true iff all arguments contain the same elements.  Always
+;;> returns true if there are less than two arguments.
+
 (define (iset= . o)
   (or (null? o)
       (let lp ((a (car o)) (ls (cdr o)))
         (or (null? ls) (and (iset2= a (car ls)) (lp (car ls) (cdr ls)))))))
 
+;;> Returns true iff the arguments are monotonically increasing, that
+;;> is each argument contains every element of all preceding
+;;> arguments.  Always returns true if there are less than two
+;;> arguments.
+
 (define (iset<= . o)
   (or (null? o)
       (let lp ((a (car o)) (ls (cdr o)))
         (or (null? ls) (and (iset2<= a (car ls)) (lp (car ls) (cdr ls)))))))
 
+;;> Returns true iff the arguments are monotonically decreasing, that
+;;> is each argument contains every element of all succeeding
+;;> arguments.  Always returns true if there are less than two
+;;> arguments.
+
 (define (iset>= . o)
   (apply iset<= (reverse o)))
 
@@ -135,6 +161,10 @@
            (right (iset-right is)))
       (if right (lp right acc) acc))))
 
+;;> The fundamental iset iterator.  Applies \var{kons} to every
+;;> element of \var{iset} along with an accumulator, starting with
+;;> \var{knil}.  Returns \var{knil} if \var{iset} is empty.
+
 (define (iset-fold kons knil iset)
   (iset-fold-node
    (lambda (is acc)
@@ -156,12 +186,19 @@
 (define (iset-for-each-node proc iset)
   (iset-fold-node (lambda (node acc) (proc node)) #f iset))
 
+;;> Runs \var{proc} on every element of iset, discarding the results.
+
 (define (iset-for-each proc iset)
   (iset-fold (lambda (i acc) (proc i)) #f iset))
 
+;;> Returns a list of every integer in \var{iset} in sorted
+;;> (increasing) order.
+
 (define (iset->list iset)
   (reverse (iset-fold cons '() iset)))
 
+;;> Returns the number of elements in \var{iset}.
+
 (define (iset-size iset)
   (iset-fold-node
    (lambda (is acc)
diff --git a/lib/chibi/parse.sld b/lib/chibi/parse.sld
index b06a4086..0e774f53 100644
--- a/lib/chibi/parse.sld
+++ b/lib/chibi/parse.sld
@@ -1,4 +1,7 @@
 
+;;> A parser combinator library with optional memoization and
+;;> convenient syntax.
+
 (define-library (chibi parse)
   (export grammar grammar/unmemoized define-grammar define-grammar/unmemoized
           call-with-parse parse parse-fully parse-fold
diff --git a/lib/chibi/string.scm b/lib/chibi/string.scm
index 388ffeab..d9f92117 100644
--- a/lib/chibi/string.scm
+++ b/lib/chibi/string.scm
@@ -2,6 +2,15 @@
 ;; Copyright (c) 2012-2015 Alex Shinn.  All rights reserved.
 ;; BSD-style license: http://synthcode.com/license.txt
 
+;;> \section{High-level API}
+
+;;> The procedures below are similar to those in SRFI 13 or other
+;;> string libraries, except instead of receiving and returning
+;;> character indexes they use opaque string cursors.
+
+;;> \procedure{(string-null? str)}
+;;> Returns true iff \var{str} is equal to the empty string \scheme{""}.
+
 (define (string-null? str)
   (equal? str ""))
 
@@ -13,8 +22,14 @@
 
 (define (complement pred) (lambda (x) (not (pred x))))
 
-(define (string-any x str)
-  (let ((pred (make-char-predicate x))
+;;> Returns true iff \var{check} is true for any character in
+;;> \var{str}.  \var{check} can be a procedure, char (to test for
+;;> \scheme{char=?} equivalence) or char-set (to test for
+;;> \var{char-set-contains?}).  Always returns false if \var{str} is
+;;> empty.
+
+(define (string-any check str)
+  (let ((pred (make-char-predicate check))
         (end (string-cursor-end str)))
     (and (string-cursor>? end (string-cursor-start str))
          (let lp ((i (string-cursor-start str)))
@@ -24,11 +39,22 @@
                  (pred ch)  ;; tail call
                  (or (pred ch) (lp i2))))))))
 
-(define (string-every x str)
-  (not (string-any (complement (make-char-predicate x)) str)))
+;;> Returns true iff \var{check} is true for every character in
+;;> \var{str}.  \var{check} can be a procedure, char or char-set as in
+;;> \scheme{string-any}.  Always returns true if \var{str} is empty.
 
-(define (string-find str x . o)
-  (let ((pred (make-char-predicate x))
+(define (string-every check str)
+  (not (string-any (complement (make-char-predicate check)) str)))
+
+;;> Returns a cursor pointing to the first position from the left in
+;;> string for which \var{check} is true.  \var{check} can be a
+;;> procedure, char or char-set as in \scheme{string-any}.  The
+;;> optional cursors \var{start} and \var{end} can specify a substring
+;;> to search, and default to the whole string.  Returns a cursor just
+;;> past the end of \var{str} if no character matches.
+
+(define (string-find str check . o)
+  (let ((pred (make-char-predicate check))
         (end (if (and (pair? o) (pair? (cdr o)))
                  (cadr o)
                  (string-cursor-end str))))
@@ -37,15 +63,22 @@
             ((pred (string-cursor-ref str i)) i)
             (else (lp (string-cursor-next str i)))))))
 
-(define (string-find? str x . o)
+;;> As above, ignoring the position and returning true iff any
+;;> character matches.
+
+(define (string-find? str check . o)
   (let ((start (if (pair? o) (car o) (string-cursor-start str)))
         (end (if (and (pair? o) (pair? (cdr o)))
                  (cadr o)
                  (string-cursor-end str))))
-    (< (string-find str x start end) end)))
+    (< (string-find str check start end) end)))
 
-(define (string-find-right str x . o)
-  (let ((pred (make-char-predicate x))
+;;> As \scheme{string-find}, but returns the position of the first
+;;> character from the right of \var{str}.  If no character matches,
+;;> returns a string cursor pointing just before \var{start}.
+
+(define (string-find-right str check . o)
+  (let ((pred (make-char-predicate check))
         (start (if (pair? o) (car o) (string-cursor-start str))))
     (let lp ((i (if (and (pair? o) (pair? (cdr o)))
                     (cadr o)
@@ -55,14 +88,32 @@
               ((pred (string-cursor-ref str i2)) i)
               (else (lp i2)))))))
 
-(define (string-skip str x . o)
-  (apply string-find str (complement (make-char-predicate x)) o))
+;;> As \scheme{string-find}, but inverts the check, returning the
+;;> position of the first character which doesn't match.
 
-(define (string-skip-right str x . o)
-  (apply string-find-right str (complement (make-char-predicate x)) o))
+(define (string-skip str check . o)
+  (apply string-find str (complement (make-char-predicate check)) o))
+
+;;> As \scheme{string-find-right}, but inverts the check, returning
+;;> the position of the first character which doesn't match.
+
+(define (string-skip-right str check . o)
+  (apply string-find-right str (complement (make-char-predicate check)) o))
+
+;;> \procedure{(string-join list-of-strings [separator])}
+;;>
+;;> Concatenates the \var{list-of-strings} and return the result as a
+;;> single string.  If \var{separator} is provided it is inserted
+;;> between each pair of strings.
 
 (define string-join string-concatenate)
 
+;;> Split \var{str} into a list of substrings separated by \var{pred},
+;;> which defaults to \scheme{#\\space}.  Multiple adjacent characters
+;;> which satisy \var{pred} will result in empty strings in the list.
+;;> If the optional \var{limit} is provided, splits into at most that
+;;> many substrings starting from the left.
+
 (define (string-split str . o)
   (let ((pred (make-char-predicate (if (pair? o) (car o) #\space)))
         (limit (if (and (pair? o) (pair? (cdr o)))
@@ -83,16 +134,28 @@
                   (reverse res)
                   (lp (string-cursor-next str j) (+ n 1) res)))))))))
 
+;;> Returns a copy of the string \var{str} with all characters
+;;> matching \var{pred} (default \scheme{#\\space}) removed from the
+;;> left.
+
 (define (string-trim-left str . o)
   (let ((pred (make-char-predicate (if (pair? o) (car o) #\space))))
     (substring-cursor str (string-skip str pred))))
 
+;;> Returns a copy of the string \var{str} with all characters
+;;> matching \var{pred} (default \scheme{#\\space}) removed from the
+;;> right.
+
 (define (string-trim-right str . o)
   (let ((pred (make-char-predicate (if (pair? o) (car o) #\space))))
     (substring-cursor str
                       (string-cursor-start str)
                       (string-skip-right str pred))))
 
+;;> Returns a copy of the string \var{str} with all characters
+;;> matching \var{pred} (default \scheme{#\\space}) removed from both
+;;> sides.
+
 (define (string-trim str . o)
   (let* ((pred (if (pair? o) (car o) #\space))
          (left (string-skip str pred))
@@ -126,14 +189,26 @@
 ;; TODO: These definitions are specific to the Chibi implementation of
 ;; cursors.  Possibly the mismatch API should be modified to allow an
 ;; efficient portable definition.
+
+;;> Returns true iff \var{prefix} is a prefix of \var{str}.
+
 (define (string-prefix? prefix str)
   (= (string-cursor-end prefix) (string-mismatch prefix str)))
 
+;;> Returns true iff \var{suffix} is a suffix of \var{str}.
+
 (define (string-suffix? suffix str)
   (= (string-cursor-prev suffix (string-cursor-start suffix))
      (- (string-mismatch-right suffix str)
         (- (string-cursor-end str) (string-cursor-end suffix)))))
 
+;;> The fundamental string iterator.  Calls \var{kons} on each
+;;> character of \var{str} and an accumulator, starting with
+;;> \var{knil}.  If multiple strings are provided, calls \var{kons} on
+;;> the corresponding characters of all strings, with the accumulator
+;;> as the final argument, and terminates when the shortest string
+;;> runs out.
+
 (define (string-fold kons knil str . los)
   (if (null? los)
       (let ((end (string-cursor-end str)))
@@ -153,6 +228,9 @@
                   (apply kons (append (map string-cursor-ref los is)
                                       (list acc)))))))))
 
+;;> Equivalent to \scheme{string-fold}, but iterates over \var{str}
+;;> from right to left.
+
 (define (string-fold-right kons knil str)
   (let ((end (string-cursor-end str)))
     (let lp ((i (string-cursor-start str)))
@@ -160,19 +238,93 @@
           knil
           (kons (string-cursor-ref str i) (lp (string-cursor-next str i)))))))
 
-(define (string-count str x)
-  (let ((pred (make-char-predicate x)))
+;;> \procedure{(string-map proc str)}
+;;>
+;;> Returns a new string composed of applying the procedure \var{proc}
+;;> to every character in \var{string}.
+
+;;> \procedure{(string-for-each proc str)}
+;;>
+;;> Apply \var{proc} to every character in \var{str} in order and
+;;> discard the result.
+
+;;> \procedure{(string-count str check)}
+;;>
+;;> Count the number of characters in \var{str} for which \var{check}
+;;> is true.
+
+(define (string-count str check)
+  (let ((pred (make-char-predicate check)))
     (string-fold (lambda (ch count) (if (pred ch) (+ count 1) count)) 0 str)))
 
+;;> \procedure{(string-contain s1 s2)}
+;;>
+;;> Returns a cursor pointing to the first position in the string
+;;> \var{s1} where \var{s2} occurs, or \scheme{#f} if there is no such
+;;> match.
+
+;;> \procedure{(mamke-string-searcher needle)}
+;;>
+;;> Partial application of \scheme{string-contain}.  Return a
+;;> procedure of one argument, a string, which runs
+;;> \scheme{(string-contain str \var{needle})}.
+
 (define (make-string-searcher needle)
   (lambda (haystack) (string-contains haystack needle)))
 
+;;> Return a copy of string \var{s} with all 26 upper-case ASCII
+;;> characters mapped to their corresponding 26 lower-case ASCII
+;;> characters.
+
 (define (string-downcase-ascii s)
   (call-with-output-string
     (lambda (out)
       (string-for-each (lambda (ch) (write-char (char-downcase ch) out)) s))))
 
+;;> Return a copy of string \var{s} with all 26 lower-case ASCII
+;;> characters mapped to their corresponding 26 upper-case ASCII
+;;> characters.
+
 (define (string-upcase-ascii s)
   (call-with-output-string
     (lambda (out)
       (string-for-each (lambda (ch) (write-char (char-upcase ch) out)) s))))
+
+;;> \section{Cursor API}
+
+;;> \procedure{(substring-cursor str i [j])}
+;;>
+;;> Returns the substring of \var{str} between \var{i} (inclusive) and
+;;> optional \var{j} (exclusive), which defaults to the end of the
+;;> string.
+
+;;> \procedure{(string-cursor-ref str i)}
+;;>
+;;> Returns the character of \var{str} at position \var{i}.
+
+;;> \procedure{(string-cursor-start str)}
+;;>
+;;> Returns a string cursor pointing to the start of \var{str}.
+
+;;> \procedure{(string-cursor-end str)}
+;;>
+;;> Returns a string cursor pointing just past the end of \var{str}.
+
+;;> \procedure{(string-cursor-next str i)}
+;;>
+;;> Returns a string cursor to the character in \var{str} just after
+;;> the cursor \var{i}.
+
+;;> \procedure{(string-cursor-prev str i)}
+;;>
+;;> Returns a string cursor to the character in \var{str} just before
+;;> the cursor \var{i}.
+
+;;> \procedure{(string-cursor<? i j)}
+;;> \procedure{(string-cursor>? i j)}
+;;> \procedure{(string-cursor=? i j)}
+;;> \procedure{(string-cursor<=? i j)}
+;;> \procedure{(string-cursor>=? i j)}
+;;>
+;;> String cursor comparators.
+;;/
diff --git a/lib/chibi/string.sld b/lib/chibi/string.sld
index 5c7256fa..bcda4cf2 100644
--- a/lib/chibi/string.sld
+++ b/lib/chibi/string.sld
@@ -1,4 +1,8 @@
 
+;;> A cursor-oriented string library.  Provides efficient string
+;;> utilities for implementations with or without fast random-access
+;;> strings.
+
 (define-library (chibi string)
   (export
    string-cursor-start string-cursor-end string-cursor-ref
diff --git a/lib/chibi/sxml.scm b/lib/chibi/sxml.scm
index a74e9a28..600c614d 100644
--- a/lib/chibi/sxml.scm
+++ b/lib/chibi/sxml.scm
@@ -77,7 +77,7 @@
   (call-with-output-string
     (lambda (out) (html-display-escaped-string str out))))
 
-;; utility to render (valid, expanded) sxml as html
+;;> Render (valid, expanded) \var{sxml} as html.
 (define (sxml-display-as-html sxml . o)
   (let ((out (if (pair? o) (car o) (current-output-port))))
     (let lp ((sxml sxml))
@@ -101,11 +101,12 @@
        ((null? sxml))
        (else (html-display-escaped-string sxml out))))))
 
+;;> Render \var{sxml} as \var{sxml}.
 (define (sxml->xml sxml)
   (call-with-output-string
     (lambda (out) (sxml-display-as-html sxml out))))
 
-;; utility to render sxml as simple text, stripping all tags
+;;> Render \var{sxml} as simple text, stripping all tags.
 (define (sxml-strip sxml)
   (call-with-output-string
     (lambda (out)
@@ -118,7 +119,7 @@
          ((string? x)
           (display x out)))))))
 
-;; utility to render sxml as text for viewing in a terminal
+;;> Render \var{sxml} as text for viewing in a terminal.
 (define (sxml-display-as-text sxml . o)
   (let ((out (if (pair? o) (car o) (current-output-port))))
     (let lp ((sxml sxml))
diff --git a/lib/chibi/sxml.sld b/lib/chibi/sxml.sld
index 18d5db11..d74c3dbf 100644
--- a/lib/chibi/sxml.sld
+++ b/lib/chibi/sxml.sld
@@ -1,4 +1,6 @@
 
+;;> Utilities to convert sxml to xml or plain text.
+
 (define-library (chibi sxml)
   (export sxml->xml sxml-display-as-html sxml-display-as-text sxml-strip
           html-escape html-tag->string)
diff --git a/tools/optimize-char-sets.scm b/tools/optimize-char-sets.scm
index db9f0214..f617f2ea 100644
--- a/tools/optimize-char-sets.scm
+++ b/tools/optimize-char-sets.scm
@@ -46,7 +46,7 @@
                                 (do ((cur (iset-cursor value)
                                           (iset-cursor-next value cur))
                                      (res '() (cons (iset-ref value cur) res)))
-                                    ((end-of-iset? cur) (reverse res)))))
+                                    ((end-of-iset? value cur) (reverse res)))))
                    (error "error in iset cursors"))
                (display "  computing intersection\n" (current-error-port))
                (let* ((iset1 (if ascii?