diff --git a/src/ikarus.boot b/src/ikarus.boot
index f8dbf57..bcdd7b6 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.io.input-strings.ss b/src/ikarus.io.input-strings.ss
index 33038e4..b48c38b 100644
--- a/src/ikarus.io.input-strings.ss
+++ b/src/ikarus.io.input-strings.ss
@@ -1,6 +1,6 @@
 
 (library (ikarus io input-strings)
-  (export open-input-string)
+  (export open-input-string with-input-from-string)
   (import 
     (ikarus system $strings)
     (ikarus system $bytevectors)
@@ -8,7 +8,7 @@
     (ikarus system $pairs)
     (ikarus system $ports)
     (ikarus system $io)
-    (except (ikarus) open-input-string))
+    (except (ikarus) open-input-string with-input-from-string))
  
   (define-syntax message-case
     (syntax-rules (else)
@@ -75,5 +75,17 @@
                     (make-input-string-handler str)
                     '#vu8())])
         port)))
+
+
+  (define with-input-from-string
+     (lambda (str proc)
+       (unless (string? str) 
+         (error 'with-input-from-string "~s is not a string" str))
+       (unless (procedure? proc)
+         (error 'with-input-from-string "~s is not a procedure" proc))
+       (let ([p (open-input-string str)])
+         (parameterize ([current-input-port p])
+           (proc)))))
+
   )
 
diff --git a/src/ikarus.numerics.ss b/src/ikarus.numerics.ss
index 1a6cd92..49bcc25 100644
--- a/src/ikarus.numerics.ss
+++ b/src/ikarus.numerics.ss
@@ -832,6 +832,66 @@
           [($fx> len 1)
            (convert-data-init str len pos? 2 ($string-ref str 1))]
           [else #f]))
+      (define (digit c radix)
+        (cond
+          [(and ($char<= #\0 c) ($char<= c #\9)) 
+           (let ([n ($fx- ($char->fixnum c) ($char->fixnum #\0))])
+             (and
+               (or ($fx>= radix 10)
+                   (and ($fx= radix 8) ($char<= c #\7))
+                   (and ($fx= radix 2) ($char<= c #\1)))
+               n))]
+          [(and ($char<= #\a c) ($char<= c #\f)) 
+           (let ([n ($fx+ 10 ($fx- ($char->fixnum c) ($char->fixnum #\a)))])
+             (and ($fx= radix 16) n))] 
+          [(and ($char<= #\A c) ($char<= c #\F)) 
+           (let ([n ($fx+ 10 ($fx- ($char->fixnum c) ($char->fixnum #\A)))])
+             (and ($fx= radix 16) n))] 
+          [else #f]))
+      (define (convert-subseq str idx len radix ac)
+        (cond
+          [($fx< idx len)
+           (let ([c (string-ref str idx)])
+             (cond
+               [(digit c radix) =>
+                (lambda (n) 
+                  (convert-subseq str ($fxadd1 idx) len radix
+                    (+ (* ac radix) n)))]
+               [else #f]))]
+          [else ac]))
+      (define (convert-init str idx len radix)
+        (cond
+          [($fx< idx len)
+           (let ([c (string-ref str idx)])
+             (cond
+               [(digit c radix) =>
+                (lambda (n) 
+                  (convert-subseq str ($fxadd1 idx) len radix n))]
+               [else #f]))]
+          [else #f]))
+      (define (convert-init-sign str idx len radix)
+        (cond
+          [($fx< idx len)
+           (let ([c (string-ref str idx)])
+             (cond
+               [(char=? c #\+)
+                (convert-init str ($fxadd1 idx) len radix)]
+               [(char=? c #\-)
+                (let ([n (convert-init str ($fxadd1 idx) len radix)])
+                  (and n (- n)))]
+               [else (convert-init str idx len radix)]))]
+          [else #f]))
+      (define (convert-radix str len)
+        (cond
+          [($fx>= len 2)
+           (let ([c (string-ref str 1)])
+             (case c
+               [(#\x #\X) (convert-init-sign str 2 len 16)]
+               [(#\b #\B) (convert-init-sign str 2 len 2)]
+               [(#\d #\D) (convert-init-sign str 2 len 10)]
+               [(#\o #\O) (convert-init-sign str 2 len 8)]
+               [else #f]))]
+          [else #f]))
       (define (convert-sign str len)
         (cond
           [($fx> len 0)
@@ -839,6 +899,7 @@
              (case c
                [(#\+) (convert-num str len #t)]
                [(#\-) (convert-num str len #f)]
+               [(#\#) (convert-radix str len)]
                [else
                 (convert-data-init str len #t 1 c)]))]
           [else #f]))
diff --git a/src/ikarus.reader.ss b/src/ikarus.reader.ss
index d02ac4b..54f281a 100644
--- a/src/ikarus.reader.ss
+++ b/src/ikarus.reader.ss
@@ -176,7 +176,7 @@
         (cond
           [(eof-object? c) '(datum . +)]
           [(delimiter? c)  '(datum . +)]
-          [(digit? c) 
+          [(digit? c)
            (read-char p)
            (cons 'datum (tokenize-number (char->num c) p))]
           [($char= c #\.)
@@ -340,6 +340,72 @@
         [(char-whitespace? c)
          (skip-whitespace p caller)]
         [else c])))
+  (module (tok-exact tok-radix)
+    (define (eof-error)
+      (error 'tokenize "eof encountered while reading a number"))
+    (define (digit? c)
+      (memq c '(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9 
+                #\a #\b #\c #\d #\e #\f #\A #\B #\C #\D #\E #\F)))
+    (define (tok-complex-sign p)
+      (error 'tok-complex-sign "not yet"))
+    (define (tok-real-decimal p)
+      (error 'tok-real-decimal "not yet"))
+    (define (tok-real-decpt p)
+      (error 'tok-real-decpt "not yet"))
+    (define (tok-real-sign p)
+      ;;; we read the sign part of a real number
+      (let ([c0 (read-char p)])
+        (cond
+          [(eof-object? c0) (eof-error)]
+          [(memq c0 '(#\.)) 
+           (cons c0 (tok-real-decpt p))]
+          [(digit? c0)
+           (cons c0 (tok-real-digit p))]
+          [(delimiter? c0) (unread-char c0 p) '()]
+          ;[(memq c0 '(#\i)) ;;; +i and -i
+          ; (list c0)]
+          [else (list c0)])))
+    (define (tok-real-digit p)
+      ;;; we did read one digit.
+      (let ([c0 (read-char p)])
+        (cond
+          [(eof-object? c0) '()]
+          [(memq c0 '(#\.))
+           (cons c0 (tok-real-decimal p))]
+          [(memq c0 '(#\- #\+)) 
+           (cons c0 (tok-complex-sign p))]
+          [(digit? c0) 
+           (cons c0 (tok-real-digit p))]
+          [(delimiter? c0) (unread-char c0 p) '()]
+          [else (list c0)])))
+    (define (tok-real p)
+      (let ([c0 (read-char p)])
+        (cond
+          [(eof-object? c0) (eof-error)]
+          [(memq c0 '(#\- #\+)) 
+           (cons c0 (tok-real-sign p))]
+          [(memq c0 '(#\.)) 
+           (cons c0 (tok-real-decpt p))]
+          [(digit? c0) 
+           (cons c0 (tok-real-digit p))]
+          [(delimiter? c0) (unread-char c0 p) '()]
+          [else (list c0)])))
+    (define (tok-exact p)
+      (error 'tokenize-exact "not yet"))
+    (define (tok-radix p)
+      (let ([c0 (peek-char p)])
+        (cond
+          [(eof-object? c0) (eof-error)]
+          [($char= c0 #\#) 
+           (read-char p)
+           (let ([c1 (read-char p)])
+             (cond
+               [(eof-object? c1) (eof-error)]
+               [(memq c1 '(#\e #\i #\E #\I))
+                (list* c0 c1 (tok-real p))]
+               [(delimiter? c1) (unread-char c1 p) (list c0)]
+               [else (list c0 c1)]))]
+          [else (tok-real p)]))))
   (define tokenize-hash/c
     (lambda (c p)
       (cond
@@ -358,38 +424,10 @@
              [else (error 'tokenize "invalid syntax near #f")]))]
         [($char= #\\ c) (tokenize-char p)]
         [($char= #\( c) 'vparen]
-        [($char= #\x c) (tokenize-hex-init p)]
         [($char= #\' c) '(macro . syntax)]
         [($char= #\; c) 'hash-semi]
         [($char= #\% c) '(macro . |#primitive|)]
         [($char= #\| c) (multiline-comment p) (tokenize p)]
-        [($char= #\b c) 
-         (let ([c (read-char p)])
-           (cond
-             [(eof-object? c) 
-              (error 'tokenize "invalid eof while reading #b")]
-             [($char= #\- c)
-              (let ([c (read-char p)])
-                (cond
-                  [(eof-object? c)
-                   (error 'tokenize "invalid eof while reading #b-")]
-                  [($char= #\0 c)
-                   (cons 'datum
-                     (* -1 (read-binary 0 '(#\0 #\-) p)))]
-                  [($char= #\1 c)
-                   (cons 'datum
-                     (* -1 (read-binary 1 '(#\1 #\-) p)))]
-                  [else 
-                   (unread-char c p)
-                   (error 'tokenize "invalid binary syntax #b-~a" c)]))]
-             [($char= #\0 c)
-              (cons 'datum (read-binary 0 '(#\0) p))]
-             [($char= #\1 c)
-              (cons 'datum (read-binary 1 '(#\1) p))]
-             [else 
-              (unread-char c p)
-              (error 'tokenize "invalid syntax #b~a" c)]
-             ))]
         [($char= #\! c) 
          (let ([e (read-char p)])
            (when (eof-object? e)
@@ -482,6 +520,44 @@
              [(eof-object? c) 
               (error 'tokenize "invalid eof object after #v")]
              [else (error 'tokenize "invalid sequence #v~a" c)]))]
+        [(memq c '(#\e #\i #\E #\I))
+         (let ([str (list->string (list* #\# c (tok-exact p)))])
+           (cond
+             [(string->number str) => (lambda (n) (cons 'datum n))]
+             [else (error 'tokenize "invalid numeric sequence ~a" str)]))]
+        [(memq c '(#\b #\B #\x #\X #\o #\O #\d #\D))
+         (let ([str (list->string (list* #\# c (tok-radix p)))])
+           (cond
+             [(string->number str) => (lambda (n) (cons 'datum n))]
+             [else (error 'tokenize "invalid numeric sequence ~a" str)]))]
+        ;[($char= #\x c) (tokenize-hex-init p)]
+        ;[(or ($char= #\b c) ($char= #\B c))
+        ; (let ([c (read-char p)])
+        ;   (cond
+        ;     [(eof-object? c) 
+        ;      (error 'tokenize "invalid eof while reading #b")]
+        ;     [($char= #\- c)
+        ;      (let ([c (read-char p)])
+        ;        (cond
+        ;          [(eof-object? c)
+        ;           (error 'tokenize "invalid eof while reading #b-")]
+        ;          [($char= #\0 c)
+        ;           (cons 'datum
+        ;             (* -1 (read-binary 0 '(#\0 #\-) p)))]
+        ;          [($char= #\1 c)
+        ;           (cons 'datum
+        ;             (* -1 (read-binary 1 '(#\1 #\-) p)))]
+        ;          [else 
+        ;           (unread-char c p)
+        ;           (error 'tokenize "invalid binary syntax #b-~a" c)]))]
+        ;     [($char= #\0 c)
+        ;      (cons 'datum (read-binary 0 '(#\0) p))]
+        ;     [($char= #\1 c)
+        ;      (cons 'datum (read-binary 1 '(#\1) p))]
+        ;     [else 
+        ;      (unread-char c p)
+        ;      (error 'tokenize "invalid syntax #b~a" c)]
+        ;     ))]
         [($char= #\@ c)
          (error 'read "FIXME: fasl read disabled")
          '(cons 'datum ($fasl-read p))]
@@ -529,7 +605,7 @@
          (let ([c (peek-char p)])
            (cond
             [(eof-object? c) '(macro . unquote)]
-            [($char= c #\@) 
+            [($char= c #\@)
              (read-char p)
              '(macro . unquote-splicing)]
             [else '(macro . unquote)]))]
@@ -539,7 +615,7 @@
         [(initial? c) 
          (let ([ls (reverse (tokenize-identifier (cons c '()) p))])
            (cons 'datum (string->symbol (list->string ls))))]
-        [($char= #\" c) 
+        [($char= #\" c)
          (let ([ls (tokenize-string '() p)])
            (cons 'datum (list->string (reverse ls))))]
         [($char= #\; c)
diff --git a/src/makefile.ss b/src/makefile.ss
index 1350943..e45c49a 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -380,6 +380,7 @@
     [output-port-name        i]
     [open-input-file         i r]
     [with-input-from-file    i r]
+    [with-input-from-string  i]
     [with-output-to-file     i r]
     [open-output-file        i r]
     [open-output-string      i]
diff --git a/src/run-tests.ss b/src/run-tests.ss
index b7b4d66..f8248aa 100755
--- a/src/run-tests.ss
+++ b/src/run-tests.ss
@@ -1,7 +1,9 @@
 #!/usr/bin/env ikarus --r6rs-script
 
 (import (ikarus)
+        (tests reader)
         (tests bytevectors))
 
+(test-reader)
 (test-bytevectors)
 (printf "Happy Happy Joy Joy\n")
diff --git a/src/tests/reader.ss b/src/tests/reader.ss
new file mode 100644
index 0000000..942705e
--- /dev/null
+++ b/src/tests/reader.ss
@@ -0,0 +1,19 @@
+(library (tests reader)
+  (export test-reader)
+  (import (ikarus) (tests framework))
+
+  (define t
+    (lambda (str)
+      (lambda (n?)
+        (and (number? n?)
+             (= (with-input-from-string str read) n?)))))
+
+  (define-syntax reader-tests
+    (syntax-rules ()
+      [(_ name str* ...)
+       (define-tests name 
+         [(t str*) (string->number str*)] ...)]))
+        
+  (reader-tests test-reader
+    "12"))
+