diff --git a/scsh/re.scm b/scsh/re.scm
index 0def23b..ba202f1 100644
--- a/scsh/re.scm
+++ b/scsh/re.scm
@@ -7,46 +7,161 @@
   "" ""
   )
 
-(define-record regexp-match
-  string
-  start	; 10 elt vec
-  end)  ; 10 elt vec
+;;; Match data for regexp matches.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-;;; Need to do error case for these three procs.
+(define-record regexp-match
+  string	; The string against which we matched.
+  start		; 10 elt vec
+  end)		; 10 elt vec
 
 (define (match:start match . maybe-index)
-  (vector-ref (regexp-match:start match)
-	      (:optional maybe-index 0)))
+  (let ((i (:optional maybe-index 0)))
+    (or (vector-ref (regexp-match:start match) i)
+	(error match:start "No sub-match found." match i))))
 
 (define (match:end match . maybe-index)
-  (vector-ref (regexp-match:end match)
-	      (:optional maybe-index 0)))
+  (let ((i (:optional maybe-index 0)))
+    (or (vector-ref (regexp-match:end match) i)
+	(error match:start "No sub-match found." match i))))
 
 (define (match:substring match . maybe-index)
-  (let ((i (:optional maybe-index 0)))
-    (substring (regexp-match:string match)
-	       (match:start match i)
-	       (match:end match i))))
-
-(define (string-match pattern string . maybe-start)
-  (apply regexp-exec (make-regexp pattern) string maybe-start))
+  (let* ((i (:optional maybe-index 0))
+	 (start (vector-ref (regexp-match:start match) i)))
+    (if start
+	(substring (regexp-match:string match)
+		   start
+		   (vector-ref (regexp-match:end match) i))
+	(error match:substring "No sub-match found." match i))))
 
 
-;;; Bogus stub definitions for low-level match routines:
+;;; Compiling regexps
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-(define regexp? string?)
-(define (make-regexp str) str)
+(define-record %regexp
+  string	; The string form of the regexp.
+  bytes		; The compiled representation, stuffed into a Scheme string.
+  ((disclose self) (list "Regexp" (%regexp:string self))))
+
+(define regexp? %regexp?)
+
+
+(define (make-regexp pattern)
+  (receive (err len) (%regexp-compiled-length pattern)
+    (if err (error err make-regexp pattern)
+	(let ((buf (make-string len)))
+	  (%regexp-compile pattern buf)
+	  (make-%regexp pattern buf)))))
+
+(define-foreign %regexp-compiled-length (re_byte_len (string pattern))
+  static-string	; Error msg or #f
+  integer)	; number of bytes needed to compile REGEXP.
+
+(define-foreign %regexp-compile (re_compile (string pattern)
+					    (string-desc bytes))
+  static-string) ; Error msg or #f
+
+
+;;; Executing compiled regexps
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define (regexp-exec regexp str . maybe-start)
   (let ((start (:optional maybe-start 0))
 	(start-vec (make-vector 10))
 	(end-vec (make-vector 10)))
-    (and (%regexp-match regexp str start start-vec end-vec)
-	 (make-regexp-match str start-vec end-vec))))
+    (receive (err match?)
+	(%regexp-exec (%regexp:bytes regexp) str start start-vec end-vec)
+      (if err (error err regexp-exec regexp str start)
+	  (and match?
+	       (make-regexp-match str start-vec end-vec))))))
+
+(define-foreign %regexp-exec (re_exec (string-desc compiled-regexp)
+				      (string s)
+				      (integer start)
+				      (vector-desc start-vec)
+				      (vector-desc end-vec))
+  static-string	; Error msg or #f
+  bool)		; Matched?
+
+
+;;; Compile&match regexps in one go
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;;; I could do this with the separate compile and execute procedures, 
+;;; but I go straight to C just for fun.
+
+(define (string-match pattern string . maybe-start)
+  (let ((start (:optional maybe-start 0))
+	(start-vec (make-vector 10))
+	(end-vec (make-vector 10)))
+    (receive (err match?) (%string-match pattern string start
+					 start-vec end-vec)
+      (if err (error err string-match pattern string start)
+	  (and match? (make-regexp-match string start-vec end-vec))))))
+
+(define-foreign %string-match (re_match (string pattern)
+					(string s)
+					(integer start)
+					(vector-desc start-vec)
+					(vector-desc end-vec))
+  static-string ; Error string or #f if all is ok.
+  bool)		; match?
+
+
+
+;;; Substitutions
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define-foreign %regexp-subst (re_subst (string-desc compiled-regexp)
+					(string match)
+					(string str)
+					(integer start)
+					(vector-desc start-vec)
+					(vector-desc end-vec)
+					(string-desc outbuf))
+  static-string	; Error msg or #f
+  integer)
+
+(define-foreign %regexp-subst-len (re_subst_len (string-desc compiled-regexp)
+						(string match)
+						(string str)
+						(integer start)
+						(vector-desc start-vec)
+						(vector-desc end-vec))
+  static-string	; Error msg or #f
+  integer)
+
+;;; What does this do?
+
+(define (regexp-subst re match replacement)
+  (let ((cr (%regexp:bytes re))
+	(str       (regexp-match:string match))
+	(start-vec (regexp-match:start  match))
+	(end-vec   (regexp-match:end    match)))
+    (receive (err out-len) (%regexp-subst-len cr str replacement 0
+					      start-vec end-vec)
+      (if err (error err regexp-subst str replacement) ; More data here
+	  (let ((out-buf (make-string out-len)))
+	    (receive (err out-len) (%regexp-subst cr str replacement 0
+						  start-vec end-vec out-buf)
+	      (if err (error err regexp-subst str replacement)
+		  (substring out-buf 0 out-len))))))))
+
+;;; Miscellaneous
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;;; I do this one in C, I'm not sure why:
+;;; It is used by MATCH-FILES.
+
+(define-foreign %filter-C-strings!
+  (filter_stringvec (string pattern) ((C "char const ** ~a") cvec))
+  static-string	; error message -- #f if no error.
+  integer)	; number of files that pass the filter.
 
 
 ;;; Convert a string into a regex pattern that matches that string exactly --
 ;;; in other words, quote the special chars with backslashes.
+
 (define (regexp-quote string)
   (let lp ((i (- (string-length string) 1))
 	   (result '()))
@@ -57,25 +172,3 @@
 	      (if (memv c '(#\[ #\] #\. #\* #\? #\( #\) #\| #\\ #\$ #\^ #\+))
 		  (cons #\\ result)
 		  result))))))
-
-(define-foreign %regexp-match/errno (reg_match (string regexp)
-					       (string s)
-					       (integer start)
-					       (vector-desc start-vec)
-					       (vector-desc end-vec))
-  static-string ; Error string or #f if all is ok.
-  bool)		; match?
-
-(define (%regexp-match regexp string start start-vec end-vec)
-  (receive (err match?) (%regexp-match/errno regexp string start
-					     start-vec end-vec)
-    (if err (error err %regexp-match regexp string start) match?)))
-
-
-;;; I do this one in C, I'm not sure why:
-;;; Used by MATCH-FILES.
-
-(define-foreign %filter-C-strings!
-  (filter_stringvec (string regexp) ((C "char const ** ~a") cvec))
-  static-string	; error message -- #f if no error.
-  integer)	; number of files that pass the filter.
diff --git a/scsh/re1.c b/scsh/re1.c
index fd7a7eb..3a4cf49 100644
--- a/scsh/re1.c
+++ b/scsh/re1.c
@@ -9,23 +9,136 @@
 /* Make sure our exports match up w/the implementation: */
 #include "re1.h"
 
-#ifndef NULL
-#define NULL 0
-#endif
-
 /* Not multi-threaded reentrant. */
 static char *regexp_error;
 
 /* Stash error msg in global. */
 void regerror(char *msg) {regexp_error = msg;}
 
+/*
+** Return NULL normally, error string on error.
+** Stash number of bytes needed for compiled regexp into `*len'
+*/
+
+char *re_byte_len(const char *re, int *len)
+{
+    int l;
+
+    regexp_error = 0;
+    *len = regcomp_len(re); 
+    return regexp_error;
+    }
+
+/*
+** Return NULL normally, error string on error.
+** Compile regexp into string described by `cr'.
+*/
+
+char *re_compile(const char *re, scheme_value cr) 
+{
+    int len = STRING_LENGTH(cr);
+    regexp *r = (regexp *) &STRING_REF(cr, 0);
+
+    regexp_error = 0;
+    r = regcomp_comp(re, r, len); 
+    return regexp_error;
+    }
+
 /* Return NULL normally, error string on error.
 ** Stash match info in start_vec and end_vec.
 ** Returns boolean match/no-match in hit.
 */
 
-char *reg_match(const char *re, const char *string, int start,
-		scheme_value start_vec, scheme_value end_vec,  int *hit)
+char *re_exec(scheme_value cr, const char *string, int start,
+	      scheme_value start_vec, scheme_value end_vec,  int *hit)
+{
+    regexp *r = (regexp *) &STRING_REF(cr, 0);
+
+    *hit = 0;
+
+    if( VECTOR_LENGTH(start_vec) != NSUBEXP )	/* These tests should */
+	return "Illegal start vector";		/* never trigger.     */
+    if( VECTOR_LENGTH(end_vec) != NSUBEXP )
+	return "Illegal end vector";
+
+    regexp_error = 0;
+    
+    if( regexec(r, string+start) ) {
+	int i;
+	for(i=0; i<NSUBEXP; i++) {
+	    const char *s = r->startp[i];
+	    const char *e = r->endp[i];
+	    VECTOR_REF(start_vec,i) = s ? ENTER_FIXNUM(s - string) : SCHFALSE;
+	    VECTOR_REF(end_vec,i)   = e ? ENTER_FIXNUM(e - string) : SCHFALSE;
+	    r->startp[i] = 0;	/* Why did Sommerfeld */
+	    r->endp[i]   = 0;	/* put these here? */
+	    }
+	*hit = 1;
+	}
+
+    return regexp_error;
+    }
+
+
+char *re_subst(scheme_value cr, const char *match,
+	       const char *src, int start,
+	       scheme_value start_vec, scheme_value end_vec,
+	       scheme_value outbuf, int *len)
+{
+    int i;
+    regexp *r = (regexp *) &STRING_REF(cr, 0);
+
+    if( VECTOR_LENGTH(start_vec) != NSUBEXP )	/* These tests should */
+	return "Illegal start vector";		/* never trigger.     */
+    if( VECTOR_LENGTH(end_vec) != NSUBEXP )
+	return "Illegal end vector";
+
+    for (i=0; i<NSUBEXP; i++) {
+	scheme_value se = VECTOR_REF(start_vec, i);
+	scheme_value ee = VECTOR_REF(end_vec, i);
+	r->startp[i] = FIXNUMP(se) ? (match + EXTRACT_FIXNUM(se)) : 0;
+	r->endp[i]   = FIXNUMP(ee) ? (match + EXTRACT_FIXNUM(ee)) : 0;
+        }
+    
+    regexp_error = 0;
+    regnsub(r, src, &STRING_REF(outbuf, 0), STRING_LENGTH(outbuf));
+    *len = strlen(&STRING_REF(outbuf, 0));
+    return regexp_error;
+    }
+
+char *re_subst_len(scheme_value cr, const char *match,
+		   const char *src, int start,
+		   scheme_value start_vec, scheme_value end_vec,
+		   int *len)
+{
+    int i;
+    regexp *r = (regexp *) &STRING_REF(cr, 0);
+
+    if( VECTOR_LENGTH(start_vec) != NSUBEXP )	/* These tests should */
+	return "Illegal start vector";		/* never trigger.     */
+    if( VECTOR_LENGTH(end_vec) != NSUBEXP )
+	return "Illegal end vector";
+
+    for (i=0; i<NSUBEXP; i++) {
+	scheme_value se = VECTOR_REF(start_vec, i);
+	scheme_value ee = VECTOR_REF(end_vec, i);
+	r->startp[i] = FIXNUMP(se) ? (match + EXTRACT_FIXNUM(se)) : 0;
+	r->endp[i]   = FIXNUMP(ee) ? (match + EXTRACT_FIXNUM(ee)) : 0;
+        }
+    
+    regexp_error = 0;
+    *len = regsublen(r, src);
+    return regexp_error;
+    }
+
+
+/* Return NULL normally, error string on error.
+** Stash match info in start_vec and end_vec.
+** Returns boolean match/no-match in hit.
+*/
+
+char *re_match(const char *re, const char *string, int start,
+	       scheme_value start_vec, scheme_value end_vec,  int *hit)
 {
     regexp *prog;
 
@@ -34,12 +147,12 @@ char *reg_match(const char *re, const char *string, int start,
     prog = regcomp(re);
     if( !prog ) return regexp_error;
 
-    if( VECTOR_LENGTH(start_vec) != NSUBEXP ) {
+    if( VECTOR_LENGTH(start_vec) != NSUBEXP ) {	    /* These two tests */
 	Free(prog);
 	return "Illegal start vector";
 	}
     
-    if( VECTOR_LENGTH(end_vec) != NSUBEXP ) {
+    if( VECTOR_LENGTH(end_vec) != NSUBEXP ) {	    /* should never trigger. */
 	Free(prog);
 	return "Illegal end vector";
 	}
@@ -47,8 +160,10 @@ char *reg_match(const char *re, const char *string, int start,
     if( regexec(prog, string+start) ) {
 	int i;
 	for(i=0; i<NSUBEXP; i++) {
-	    VECTOR_REF(start_vec,i) = ENTER_FIXNUM(prog->startp[i] - string);
-	    VECTOR_REF(end_vec,i)   = ENTER_FIXNUM(prog->endp[i]   - string);
+	    const char *s = prog->startp[i];
+	    const char *e = prog->endp[i];
+	    VECTOR_REF(start_vec,i) = s ? ENTER_FIXNUM(s - string) : SCHFALSE;
+	    VECTOR_REF(end_vec,i)   = e ? ENTER_FIXNUM(e - string) : SCHFALSE;
 	    }
 	*hit = 1;
 	}
diff --git a/scsh/re1.h b/scsh/re1.h
index 7a1762d..3938f7e 100644
--- a/scsh/re1.h
+++ b/scsh/re1.h
@@ -1,6 +1,24 @@
-char *reg_match(const char *re, const char *string, int start,
-		scheme_value start_vec, scheme_value end_vec,
-		int *hit);
+/* Exports from re1.c */
+
+char *re_byte_len(const char *re, int *len);
+char *re_compile(const char *re, scheme_value target);
+
+char *re_exec(scheme_value cr, const char *string, int start,
+	      scheme_value start_vec, scheme_value end_vec,  int *hit);
+
+char *re_match(const char *re, const char *string, int start,
+	       scheme_value start_vec, scheme_value end_vec,
+	       int *hit);
+
+char *re_subst_len(scheme_value cr, const char *match,
+		   const char *src, int start,
+		   scheme_value start_vec, scheme_value end_vec,
+		   int *len);
+
+char *re_subst(scheme_value cr, const char *match,
+	       const char *src, int start,
+	       scheme_value start_vec, scheme_value end_vec,
+	       scheme_value outbuf, int *len);
 
 char *filter_stringvec(const char *re, char const **stringvec,
 		       int *nummatch);