Move base32 code to (guix base32).

* guix/utils.scm (bytevector-quintet-ref, bytevector-quintet-ref-right,
  bytevector-quintet-length, bytevector-quintet-fold,
  bytevector-quintet-fold-right, make-bytevector->base32-string,
  %nix-base32-chars, %rfc4648-base32-chars, bytevector->base32-string,
  bytevector->nix-base32-string, bytevector-quintet-set!,
  bytevector-quintet-set-right!, base32-string-unfold,
  base32-string-unfold-right, make-base32-string->bytevector,
  base32-string->bytevector, nix-base32-string->bytevector): Move to...
* guix/base32.scm: ... here.  New file.

* tests/utils.scm (%nix-hash, "bytevector->base32-string",
  "base32-string->bytevector", "nix-base32-string->bytevector", "sha256
  & bytevector->base32-string"): Move to...
* tests/base32.scm: ... here.  New file

* guix-download.in, guix/derivations.scm, guix/packages.scm,
  guix/snix.scm, tests/builders.scm, tests/derivations.scm: Adjust
  accordingly.
* guix.scm (%public-modules): Add `base32'.

5 files changed, 292 insertions, 263 deletions

diff --git a/guix/base32.scm b/guix/base32.scm
new file mode 100644
index 0000000000..6f0a92bd99
--- /dev/null
+++ b/guix/base32.scm
@@ -0,0 +1,288 @@
+;;; Guix --- Nix package management from Guile.         -*- coding: utf-8 -*-
+;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of Guix.
+;;;
+;;; Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix base32)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-60)
+  #:use-module (rnrs bytevectors)
+  #:use-module (ice-9 vlist)
+  #:export (bytevector-quintet-length
+            bytevector->base32-string
+            bytevector->nix-base32-string
+            base32-string->bytevector
+            nix-base32-string->bytevector))
+
+;;; Commentary:
+;;;
+;;; A generic, customizable to convert bytevectors to/from a base32
+;;; representation.
+;;;
+;;; Code:
+
+(define bytevector-quintet-ref
+  (let* ((ref  bytevector-u8-ref)
+         (ref+ (lambda (bv offset)
+                 (let ((o (+ 1 offset)))
+                   (if (>= o (bytevector-length bv))
+                       0
+                       (bytevector-u8-ref bv o)))))
+         (ref0 (lambda (bv offset)
+                 (bit-field (ref bv offset) 3 8)))
+         (ref1 (lambda (bv offset)
+                 (logior (ash (bit-field (ref bv offset) 0 3) 2)
+                         (bit-field (ref+ bv offset) 6 8))))
+         (ref2 (lambda (bv offset)
+                 (bit-field (ref bv offset) 1 6)))
+         (ref3 (lambda (bv offset)
+                 (logior (ash (bit-field (ref bv offset) 0 1) 4)
+                         (bit-field (ref+ bv offset) 4 8))))
+         (ref4 (lambda (bv offset)
+                 (logior (ash (bit-field (ref bv offset) 0 4) 1)
+                         (bit-field (ref+ bv offset) 7 8))))
+         (ref5 (lambda (bv offset)
+                 (bit-field (ref bv offset) 2 7)))
+         (ref6 (lambda (bv offset)
+                 (logior (ash (bit-field (ref bv offset) 0 2) 3)
+                         (bit-field (ref+ bv offset) 5 8))))
+         (ref7 (lambda (bv offset)
+                 (bit-field (ref bv offset) 0 5)))
+         (refs (vector ref0 ref1 ref2 ref3 ref4 ref5 ref6 ref7)))
+    (lambda (bv index)
+      "Return the INDEXth quintet of BV."
+      (let ((p (vector-ref refs (modulo index 8))))
+        (p bv (quotient (* index 5) 8))))))
+
+(define bytevector-quintet-ref-right
+  (let* ((ref  bytevector-u8-ref)
+         (ref+ (lambda (bv offset)
+                 (let ((o (+ 1 offset)))
+                   (if (>= o (bytevector-length bv))
+                       0
+                       (bytevector-u8-ref bv o)))))
+         (ref0 (lambda (bv offset)
+                 (bit-field (ref bv offset) 0 5)))
+         (ref1 (lambda (bv offset)
+                 (logior (bit-field (ref bv offset) 5 8)
+                         (ash (bit-field (ref+ bv offset) 0 2) 3))))
+         (ref2 (lambda (bv offset)
+                 (bit-field (ref bv offset) 2 7)))
+         (ref3 (lambda (bv offset)
+                 (logior (bit-field (ref bv offset) 7 8)
+                         (ash (bit-field (ref+ bv offset) 0 4) 1))))
+         (ref4 (lambda (bv offset)
+                 (logior (bit-field (ref bv offset) 4 8)
+                         (ash (bit-field (ref+ bv offset) 0 1) 4))))
+         (ref5 (lambda (bv offset)
+                 (bit-field (ref bv offset) 1 6)))
+         (ref6 (lambda (bv offset)
+                 (logior (bit-field (ref bv offset) 6 8)
+                         (ash (bit-field (ref+ bv offset) 0 3) 2))))
+         (ref7 (lambda (bv offset)
+                 (bit-field (ref bv offset) 3 8)))
+         (refs (vector ref0 ref1 ref2 ref3 ref4 ref5 ref6 ref7)))
+    (lambda (bv index)
+      "Return the INDEXth quintet of BV, assuming quintets start from the
+least-significant bits, contrary to what RFC 4648 describes."
+      (let ((p (vector-ref refs (modulo index 8))))
+        (p bv (quotient (* index 5) 8))))))
+
+(define (bytevector-quintet-length bv)
+  "Return the number of quintets (including truncated ones) available in BV."
+  (ceiling (/ (* (bytevector-length bv) 8) 5)))
+
+(define (bytevector-quintet-fold proc init bv)
+  "Return the result of applying PROC to each quintet of BV and the result of
+the previous application or INIT."
+  (define len
+    (bytevector-quintet-length bv))
+
+  (let loop ((i 0)
+             (r init))
+    (if (= i len)
+        r
+        (loop (1+ i) (proc (bytevector-quintet-ref bv i) r)))))
+
+(define (bytevector-quintet-fold-right proc init bv)
+  "Return the result of applying PROC to each quintet of BV and the result of
+the previous application or INIT."
+  (define len
+    (bytevector-quintet-length bv))
+
+  (let loop ((i len)
+             (r init))
+    (if (zero? i)
+        r
+        (let ((j (- i 1)))
+          (loop j (proc (bytevector-quintet-ref-right bv j) r))))))
+
+(define (make-bytevector->base32-string quintet-fold base32-chars)
+  (lambda (bv)
+    "Return a base32 encoding of BV using BASE32-CHARS as the alphabet."
+    (let ((chars (quintet-fold (lambda (q r)
+                                 (cons (vector-ref base32-chars q)
+                                       r))
+                               '()
+                               bv)))
+      (list->string (reverse chars)))))
+
+(define %nix-base32-chars
+  ;; See `libutil/hash.cc'.
+  #(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9
+    #\a #\b #\c #\d #\f #\g #\h #\i #\j #\k #\l #\m #\n
+    #\p #\q #\r #\s #\v #\w #\x #\y #\z))
+
+(define %rfc4648-base32-chars
+  #(#\a #\b #\c #\d #\e #\f #\g #\h #\i #\j #\k #\l #\m
+    #\n #\o #\p #\q #\r #\s #\t #\u #\v #\w #\x #\y #\z
+    #\2 #\3 #\4 #\5 #\6 #\7))
+
+(define bytevector->base32-string
+  (make-bytevector->base32-string bytevector-quintet-fold
+                                  %rfc4648-base32-chars))
+
+(define bytevector->nix-base32-string
+  (make-bytevector->base32-string bytevector-quintet-fold-right
+                                  %nix-base32-chars))
+
+
+(define bytevector-quintet-set!
+  (let* ((setq! (lambda (bv offset start stop value)
+                  (let ((v (bytevector-u8-ref bv offset))
+                        (w (arithmetic-shift value start))
+                        (m (bitwise-xor (1- (expt 2 stop))
+                                        (1- (expt 2 start)))))
+                    (bytevector-u8-set! bv offset
+                                        (bitwise-merge m w v)))))
+         (set0! (lambda (bv offset value)
+                  (setq! bv offset 3 8 value)))
+         (set1! (lambda (bv offset value)
+                  (setq! bv offset 0 3 (bit-field value 2 5))
+                  (or (= (+ 1 offset) (bytevector-length bv))
+                      (setq! bv (+ 1 offset) 6 8 (bit-field value 0 2)))))
+         (set2! (lambda (bv offset value)
+                  (setq! bv offset 1 6 value)))
+         (set3! (lambda (bv offset value)
+                  (setq! bv offset 0 1 (bit-field value 4 5))
+                  (or (= (+ 1 offset) (bytevector-length bv))
+                      (setq! bv (+ 1 offset) 4 8 (bit-field value 0 4)))))
+         (set4! (lambda (bv offset value)
+                  (setq! bv offset 0 4 (bit-field value 1 5))
+                  (or (= (+ 1 offset) (bytevector-length bv))
+                      (setq! bv (+ 1 offset) 7 8  (bit-field value 0 1)))))
+         (set5! (lambda (bv offset value)
+                  (setq! bv offset 2 7 value)))
+         (set6! (lambda (bv offset value)
+                  (setq! bv offset 0 2 (bit-field value 3 5))
+                  (or (= (+ 1 offset) (bytevector-length bv))
+                      (setq! bv (+ 1 offset) 5 8 (bit-field value 0 3)))))
+         (set7! (lambda (bv offset value)
+                  (setq! bv offset 0 5 value)))
+         (sets  (vector set0! set1! set2! set3! set4! set5! set6! set7!)))
+    (lambda (bv index value)
+      "Set the INDEXth quintet of BV to VALUE."
+      (let ((p (vector-ref sets (modulo index 8))))
+        (p bv (quotient (* index 5) 8) (logand value #x1f))))))
+
+(define bytevector-quintet-set-right!
+  (let* ((setq! (lambda (bv offset start stop value)
+                  (let ((v (bytevector-u8-ref bv offset))
+                        (w (arithmetic-shift value start))
+                        (m (bitwise-xor (1- (expt 2 stop))
+                                        (1- (expt 2 start)))))
+                    (bytevector-u8-set! bv offset
+                                        (bitwise-merge m w v)))))
+         (set0! (lambda (bv offset value)
+                  (setq! bv offset 0 5 value)))
+         (set1! (lambda (bv offset value)
+                  (setq! bv offset 5 8 (bit-field value 0 3))
+                  (or (= (+ 1 offset) (bytevector-length bv))
+                      (setq! bv (+ 1 offset) 0 2 (bit-field value 3 5)))))
+         (set2! (lambda (bv offset value)
+                  (setq! bv offset 2 7 value)))
+         (set3! (lambda (bv offset value)
+                  (setq! bv offset 7 8 (bit-field value 0 1))
+                  (or (= (+ 1 offset) (bytevector-length bv))
+                      (setq! bv (+ 1 offset) 0 4 (bit-field value 1 5)))))
+         (set4! (lambda (bv offset value)
+                  (setq! bv offset 4 8 (bit-field value 0 4))
+                  (or (= (+ 1 offset) (bytevector-length bv))
+                      (setq! bv (+ 1 offset) 0 1 (bit-field value 4 5)))))
+         (set5! (lambda (bv offset value)
+                  (setq! bv offset 1 6 value)))
+         (set6! (lambda (bv offset value)
+                  (setq! bv offset 6 8 (bit-field value 0 2))
+                  (or (= (+ 1 offset) (bytevector-length bv))
+                      (setq! bv (+ 1 offset) 0 3 (bit-field value 2 5)))))
+         (set7! (lambda (bv offset value)
+                  (setq! bv offset 3 8 value)))
+         (sets  (vector set0! set1! set2! set3! set4! set5! set6! set7!)))
+    (lambda (bv index value)
+      "Set the INDEXth quintet of BV to VALUE, assuming quintets start from
+the least-significant bits."
+      (let ((p (vector-ref sets (modulo index 8))))
+        (p bv (quotient (* index 5) 8) (logand value #x1f))))))
+
+(define (base32-string-unfold f s)
+  "Given procedure F which, when applied to a character, returns the
+corresponding quintet, return the bytevector corresponding to string S."
+  (define len (string-length s))
+
+  (let ((bv (make-bytevector (quotient (* len 5) 8))))
+    (string-fold (lambda (chr index)
+                   (bytevector-quintet-set! bv index (f chr))
+                   (+ 1 index))
+                 0
+                 s)
+    bv))
+
+(define (base32-string-unfold-right f s)
+  "Given procedure F which, when applied to a character, returns the
+corresponding quintet, return the bytevector corresponding to string S,
+starting from the right of S."
+  (define len (string-length s))
+
+  (let ((bv (make-bytevector (quotient (* len 5) 8))))
+    (string-fold-right (lambda (chr index)
+                         (bytevector-quintet-set-right! bv index (f chr))
+                         (+ 1 index))
+                       0
+                       s)
+    bv))
+
+(define (make-base32-string->bytevector base32-string-unfold base32-chars)
+  (let ((char->value (let loop ((i 0)
+                                (v vlist-null))
+                       (if (= i (vector-length base32-chars))
+                           v
+                           (loop (+ 1 i)
+                                 (vhash-consv (vector-ref base32-chars i)
+                                              i v))))))
+    (lambda (s)
+      "Return the binary representation of base32 string S as a bytevector."
+      (base32-string-unfold (lambda (chr)
+                              (or (and=> (vhash-assv chr char->value) cdr)
+                                  (error "invalid base32 character" chr)))
+                            s))))
+
+(define base32-string->bytevector
+  (make-base32-string->bytevector base32-string-unfold %rfc4648-base32-chars))
+
+(define nix-base32-string->bytevector
+  (make-base32-string->bytevector base32-string-unfold-right %nix-base32-chars))
+
+;;; base32.scm ends here
diff --git a/guix/derivations.scm b/guix/derivations.scm
index cbf755ab63..cda1f065d4 100644
--- a/guix/derivations.scm
+++ b/guix/derivations.scm
@@ -26,6 +26,7 @@
   #:use-module (ice-9 rdelim)
   #:use-module (guix store)
   #:use-module (guix utils)
+  #:use-module (guix base32)
   #:export (<derivation>
             derivation?
             derivation-outputs
diff --git a/guix/packages.scm b/guix/packages.scm
index 9d1dbe7dc4..23761f4101 100644
--- a/guix/packages.scm
+++ b/guix/packages.scm
@@ -19,6 +19,7 @@
 (define-module (guix packages)
   #:use-module (guix utils)
   #:use-module (guix store)
+  #:use-module (guix base32)
   #:use-module (guix build-system)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-1)
diff --git a/guix/snix.scm b/guix/snix.scm
index ef98eb42a0..c6a9bee6a7 100644
--- a/guix/snix.scm
+++ b/guix/snix.scm
@@ -32,6 +32,7 @@
   #:use-module (system foreign)
   #:use-module (rnrs bytevectors)
   #:use-module (guix utils)
+  #:use-module (guix base32)
   #:use-module (guix config)
   #:export (open-nixpkgs
             xml->snix
diff --git a/guix/utils.scm b/guix/utils.scm
index fa5abadc7a..ff8730aa63 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -33,12 +33,7 @@
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:autoload   (system foreign) (pointer->procedure)
-  #:export (bytevector-quintet-length
-            bytevector->base32-string
-            bytevector->nix-base32-string
-            bytevector->base16-string
-            base32-string->bytevector
-            nix-base32-string->bytevector
+  #:export (bytevector->base16-string
             base16-string->bytevector
             sha256
 
@@ -81,263 +76,6 @@ evaluate to a simple datum."
 
 
 ;;;
-;;; Base 32.
-;;;
-
-(define bytevector-quintet-ref
-  (let* ((ref  bytevector-u8-ref)
-         (ref+ (lambda (bv offset)
-                 (let ((o (+ 1 offset)))
-                   (if (>= o (bytevector-length bv))
-                       0
-                       (bytevector-u8-ref bv o)))))
-         (ref0 (lambda (bv offset)
-                 (bit-field (ref bv offset) 3 8)))
-         (ref1 (lambda (bv offset)
-                 (logior (ash (bit-field (ref bv offset) 0 3) 2)
-                         (bit-field (ref+ bv offset) 6 8))))
-         (ref2 (lambda (bv offset)
-                 (bit-field (ref bv offset) 1 6)))
-         (ref3 (lambda (bv offset)
-                 (logior (ash (bit-field (ref bv offset) 0 1) 4)
-                         (bit-field (ref+ bv offset) 4 8))))
-         (ref4 (lambda (bv offset)
-                 (logior (ash (bit-field (ref bv offset) 0 4) 1)
-                         (bit-field (ref+ bv offset) 7 8))))
-         (ref5 (lambda (bv offset)
-                 (bit-field (ref bv offset) 2 7)))
-         (ref6 (lambda (bv offset)
-                 (logior (ash (bit-field (ref bv offset) 0 2) 3)
-                         (bit-field (ref+ bv offset) 5 8))))
-         (ref7 (lambda (bv offset)
-                 (bit-field (ref bv offset) 0 5)))
-         (refs (vector ref0 ref1 ref2 ref3 ref4 ref5 ref6 ref7)))
-    (lambda (bv index)
-      "Return the INDEXth quintet of BV."
-      (let ((p (vector-ref refs (modulo index 8))))
-        (p bv (quotient (* index 5) 8))))))
-
-(define bytevector-quintet-ref-right
-  (let* ((ref  bytevector-u8-ref)
-         (ref+ (lambda (bv offset)
-                 (let ((o (+ 1 offset)))
-                   (if (>= o (bytevector-length bv))
-                       0
-                       (bytevector-u8-ref bv o)))))
-         (ref0 (lambda (bv offset)
-                 (bit-field (ref bv offset) 0 5)))
-         (ref1 (lambda (bv offset)
-                 (logior (bit-field (ref bv offset) 5 8)
-                         (ash (bit-field (ref+ bv offset) 0 2) 3))))
-         (ref2 (lambda (bv offset)
-                 (bit-field (ref bv offset) 2 7)))
-         (ref3 (lambda (bv offset)
-                 (logior (bit-field (ref bv offset) 7 8)
-                         (ash (bit-field (ref+ bv offset) 0 4) 1))))
-         (ref4 (lambda (bv offset)
-                 (logior (bit-field (ref bv offset) 4 8)
-                         (ash (bit-field (ref+ bv offset) 0 1) 4))))
-         (ref5 (lambda (bv offset)
-                 (bit-field (ref bv offset) 1 6)))
-         (ref6 (lambda (bv offset)
-                 (logior (bit-field (ref bv offset) 6 8)
-                         (ash (bit-field (ref+ bv offset) 0 3) 2))))
-         (ref7 (lambda (bv offset)
-                 (bit-field (ref bv offset) 3 8)))
-         (refs (vector ref0 ref1 ref2 ref3 ref4 ref5 ref6 ref7)))
-    (lambda (bv index)
-      "Return the INDEXth quintet of BV, assuming quintets start from the
-least-significant bits, contrary to what RFC 4648 describes."
-      (let ((p (vector-ref refs (modulo index 8))))
-        (p bv (quotient (* index 5) 8))))))
-
-(define (bytevector-quintet-length bv)
-  "Return the number of quintets (including truncated ones) available in BV."
-  (ceiling (/ (* (bytevector-length bv) 8) 5)))
-
-(define (bytevector-quintet-fold proc init bv)
-  "Return the result of applying PROC to each quintet of BV and the result of
-the previous application or INIT."
-  (define len
-    (bytevector-quintet-length bv))
-
-  (let loop ((i 0)
-             (r init))
-    (if (= i len)
-        r
-        (loop (1+ i) (proc (bytevector-quintet-ref bv i) r)))))
-
-(define (bytevector-quintet-fold-right proc init bv)
-  "Return the result of applying PROC to each quintet of BV and the result of
-the previous application or INIT."
-  (define len
-    (bytevector-quintet-length bv))
-
-  (let loop ((i len)
-             (r init))
-    (if (zero? i)
-        r
-        (let ((j (- i 1)))
-          (loop j (proc (bytevector-quintet-ref-right bv j) r))))))
-
-(define (make-bytevector->base32-string quintet-fold base32-chars)
-  (lambda (bv)
-    "Return a base32 encoding of BV using BASE32-CHARS as the alphabet."
-    (let ((chars (quintet-fold (lambda (q r)
-                                 (cons (vector-ref base32-chars q)
-                                       r))
-                               '()
-                               bv)))
-      (list->string (reverse chars)))))
-
-(define %nix-base32-chars
-  ;; See `libutil/hash.cc'.
-  #(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9
-    #\a #\b #\c #\d #\f #\g #\h #\i #\j #\k #\l #\m #\n
-    #\p #\q #\r #\s #\v #\w #\x #\y #\z))
-
-(define %rfc4648-base32-chars
-  #(#\a #\b #\c #\d #\e #\f #\g #\h #\i #\j #\k #\l #\m
-    #\n #\o #\p #\q #\r #\s #\t #\u #\v #\w #\x #\y #\z
-    #\2 #\3 #\4 #\5 #\6 #\7))
-
-(define bytevector->base32-string
-  (make-bytevector->base32-string bytevector-quintet-fold
-                                  %rfc4648-base32-chars))
-
-(define bytevector->nix-base32-string
-  (make-bytevector->base32-string bytevector-quintet-fold-right
-                                  %nix-base32-chars))
-
-
-(define bytevector-quintet-set!
-  (let* ((setq! (lambda (bv offset start stop value)
-                  (let ((v (bytevector-u8-ref bv offset))
-                        (w (arithmetic-shift value start))
-                        (m (bitwise-xor (1- (expt 2 stop))
-                                        (1- (expt 2 start)))))
-                    (bytevector-u8-set! bv offset
-                                        (bitwise-merge m w v)))))
-         (set0! (lambda (bv offset value)
-                  (setq! bv offset 3 8 value)))
-         (set1! (lambda (bv offset value)
-                  (setq! bv offset 0 3 (bit-field value 2 5))
-                  (or (= (+ 1 offset) (bytevector-length bv))
-                      (setq! bv (+ 1 offset) 6 8 (bit-field value 0 2)))))
-         (set2! (lambda (bv offset value)
-                  (setq! bv offset 1 6 value)))
-         (set3! (lambda (bv offset value)
-                  (setq! bv offset 0 1 (bit-field value 4 5))
-                  (or (= (+ 1 offset) (bytevector-length bv))
-                      (setq! bv (+ 1 offset) 4 8 (bit-field value 0 4)))))
-         (set4! (lambda (bv offset value)
-                  (setq! bv offset 0 4 (bit-field value 1 5))
-                  (or (= (+ 1 offset) (bytevector-length bv))
-                      (setq! bv (+ 1 offset) 7 8  (bit-field value 0 1)))))
-         (set5! (lambda (bv offset value)
-                  (setq! bv offset 2 7 value)))
-         (set6! (lambda (bv offset value)
-                  (setq! bv offset 0 2 (bit-field value 3 5))
-                  (or (= (+ 1 offset) (bytevector-length bv))
-                      (setq! bv (+ 1 offset) 5 8 (bit-field value 0 3)))))
-         (set7! (lambda (bv offset value)
-                  (setq! bv offset 0 5 value)))
-         (sets  (vector set0! set1! set2! set3! set4! set5! set6! set7!)))
-    (lambda (bv index value)
-      "Set the INDEXth quintet of BV to VALUE."
-      (let ((p (vector-ref sets (modulo index 8))))
-        (p bv (quotient (* index 5) 8) (logand value #x1f))))))
-
-(define bytevector-quintet-set-right!
-  (let* ((setq! (lambda (bv offset start stop value)
-                  (let ((v (bytevector-u8-ref bv offset))
-                        (w (arithmetic-shift value start))
-                        (m (bitwise-xor (1- (expt 2 stop))
-                                        (1- (expt 2 start)))))
-                    (bytevector-u8-set! bv offset
-                                        (bitwise-merge m w v)))))
-         (set0! (lambda (bv offset value)
-                  (setq! bv offset 0 5 value)))
-         (set1! (lambda (bv offset value)
-                  (setq! bv offset 5 8 (bit-field value 0 3))
-                  (or (= (+ 1 offset) (bytevector-length bv))
-                      (setq! bv (+ 1 offset) 0 2 (bit-field value 3 5)))))
-         (set2! (lambda (bv offset value)
-                  (setq! bv offset 2 7 value)))
-         (set3! (lambda (bv offset value)
-                  (setq! bv offset 7 8 (bit-field value 0 1))
-                  (or (= (+ 1 offset) (bytevector-length bv))
-                      (setq! bv (+ 1 offset) 0 4 (bit-field value 1 5)))))
-         (set4! (lambda (bv offset value)
-                  (setq! bv offset 4 8 (bit-field value 0 4))
-                  (or (= (+ 1 offset) (bytevector-length bv))
-                      (setq! bv (+ 1 offset) 0 1 (bit-field value 4 5)))))
-         (set5! (lambda (bv offset value)
-                  (setq! bv offset 1 6 value)))
-         (set6! (lambda (bv offset value)
-                  (setq! bv offset 6 8 (bit-field value 0 2))
-                  (or (= (+ 1 offset) (bytevector-length bv))
-                      (setq! bv (+ 1 offset) 0 3 (bit-field value 2 5)))))
-         (set7! (lambda (bv offset value)
-                  (setq! bv offset 3 8 value)))
-         (sets  (vector set0! set1! set2! set3! set4! set5! set6! set7!)))
-    (lambda (bv index value)
-      "Set the INDEXth quintet of BV to VALUE, assuming quintets start from
-the least-significant bits."
-      (let ((p (vector-ref sets (modulo index 8))))
-        (p bv (quotient (* index 5) 8) (logand value #x1f))))))
-
-(define (base32-string-unfold f s)
-  "Given procedure F which, when applied to a character, returns the
-corresponding quintet, return the bytevector corresponding to string S."
-  (define len (string-length s))
-
-  (let ((bv (make-bytevector (quotient (* len 5) 8))))
-    (string-fold (lambda (chr index)
-                   (bytevector-quintet-set! bv index (f chr))
-                   (+ 1 index))
-                 0
-                 s)
-    bv))
-
-(define (base32-string-unfold-right f s)
-  "Given procedure F which, when applied to a character, returns the
-corresponding quintet, return the bytevector corresponding to string S,
-starting from the right of S."
-  (define len (string-length s))
-
-  (let ((bv (make-bytevector (quotient (* len 5) 8))))
-    (string-fold-right (lambda (chr index)
-                         (bytevector-quintet-set-right! bv index (f chr))
-                         (+ 1 index))
-                       0
-                       s)
-    bv))
-
-(define (make-base32-string->bytevector base32-string-unfold base32-chars)
-  (let ((char->value (let loop ((i 0)
-                                (v vlist-null))
-                       (if (= i (vector-length base32-chars))
-                           v
-                           (loop (+ 1 i)
-                                 (vhash-consv (vector-ref base32-chars i)
-                                              i v))))))
-    (lambda (s)
-      "Return the binary representation of base32 string S as a bytevector."
-      (base32-string-unfold (lambda (chr)
-                              (or (and=> (vhash-assv chr char->value) cdr)
-                                  (error "invalid base32 character" chr)))
-                            s))))
-
-(define base32-string->bytevector
-  (make-base32-string->bytevector base32-string-unfold %rfc4648-base32-chars))
-
-(define nix-base32-string->bytevector
-  (make-base32-string->bytevector base32-string-unfold-right %nix-base32-chars))
-
-
-
-;;;
 ;;; Base 16.
 ;;;