remove utils.macros.scm as it is no longer needed

.gitignore

@@ -1,5 +1,4 @@
 *.o
 *.import.scm
-*.link
 sexc
 sex-tests

Makefile

@@ -1,60 +1,53 @@
 CHICKEN_C = csc
-CSC_FLAGS += -K prefix -static
-# What and why:
-# -emit-all-import-libraries: Emit import-libraries for all defined modules.
-#    Used to generate .import.scm files so compiler would know how to use the modules.
-#    Without it, csc fails with "cannot import from undefined module" error.
-# -module-registration: Always  generate  module registration code, even when
-#    import libraries are emitted. Enables us to import from our modules at run time.
-#    Used in macros, where we inject `(import (only sex-macros cat))' before the macro body.
-#    Without it, sexc compiles scuccessfully, but is unable to process macros, failing with
-#    "during expansion of (import ...) - cannot import from undefined module: sex-macros"
-#     error.
-# -c: Stop after compilation to object files. This one is obvious.
-
-MODULE_FLAGS = -emit-all-import-libraries -module-registration -c
+CSC_FLAGS += -K prefix
 
 # Order matters, since module check correctness on compilation
-MODULES = utils sex-macros reader sex-modules semen sex-fmt-c fmt-c-writer sexc
+MODULES = utils macros reader module-system semen sex-fmt-c fmt-c-writer sexc
 OBJ = $(MODULES:%=%.o)
+IMPORTS = $(MODULES:%=%.import.scm)
+LINK = $(MODULES:%=%.link)
 
-sexc: $(OBJ) main.scm
-	$(CHICKEN_C) $(CSC_FLAGS) main.scm -o sexc-tmp -link sexc
-        # otherwise csc hangs, probably because it tries to compile to sexc.o first
-	mv sexc-tmp sexc
+sexc: $(OBJ) main.o
+	$(CHICKEN_C) $(CSC_FLAGS) $^ -o $@
+
+main.o: main.scm
+	$(CHICKEN_C) $(CSC_FLAGS) $< -c -o $@ -link sexc
 
 #------------------------------------------------------------------
 
-utils.o: utils.module.scm utils.scm
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) utils.module.scm -o utils.o -unit utils
+utils.o: utils.scm
+	$(CHICKEN_C) $(CSC_FLAGS) utils.scm -e -c -J -o utils.o -unit utils
 
-sex-macros.o: sex-macros.module.scm sex-macros.scm
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) sex-macros.module.scm -o sex-macros.o -unit sex-macros
+macros.o: macros.scm
+	$(CHICKEN_C) $(CSC_FLAGS) macros.scm -e -c -J -o macros.o -unit macros
 
-reader.o: reader.module.scm reader.scm
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) reader.module.scm -o reader.o -unit reader
+reader.o:
+	$(CHICKEN_C) $(CSC_FLAGS) reader.scm -e -c -J -o reader.o -unit reader
 
-sex-modules.o: sex-modules.module.scm sex-modules.scm reader.o utils.o
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) sex-modules.module.scm -o sex-modules.o -unit sex-modules -link reader,utils
+module-system.o: module-system.scm reader.import.scm utils.import.scm
+	$(CHICKEN_C) $(CSC_FLAGS) module-system.scm -e -c -J -o module-system.o -unit module-system -link utils
 
-semen.o: semen.module.scm semen.scm sex-macros.o sex-modules.o utils.o
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) semen.module.scm -o semen.o -unit semen -link sex-macros,sex-modules,utils
+semen.o: semen.scm macros.import.scm module-system.import.scm utils.import.scm
+	$(CHICKEN_C) $(CSC_FLAGS) semen.scm -e -c -J -o semen.o -unit semen -link macros -link module-system -link utils
 
-sex-fmt-c.o: sex-fmt-c.scm
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) sex-fmt-c.scm -o sex-fmt-c.o -unit sex-fmt-c
+fmt-c-writer.o: fmt-c-writer.scm sex-fmt-c.import.scm utils.import.scm
+	$(CHICKEN_C) $(CSC_FLAGS) fmt-c-writer.scm -e -c -J -o fmt-c-writer.o -unit fmt-c-writer -link sex-fmt-c -link utils
 
-fmt-c-writer.o: fmt-c-writer.module.scm fmt-c-writer.scm sex-fmt-c.o utils.o
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) fmt-c-writer.module.scm -o fmt-c-writer.o -unit fmt-c-writer -link sex-fmt-c,utils
+sexc.o: sexc.scm fmt-c-writer.import.scm macros.import.scm module-system.import.scm reader.import.scm semen.import.scm utils.import.scm
+	$(CHICKEN_C) $(CSC_FLAGS) sexc.scm -e -c -J -o sexc.o -unit sexc -link fmt-c-writer -link macros -link module-system -link reader -link semen -link utils
 
-sexc.o: sexc.module.scm sexc.scm fmt-c-writer.o sex-macros.o sex-modules.o reader.o semen.o utils.o
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) sexc.module.scm -o sexc.o -unit sexc -link fmt-c-writer,sex-macros,sex-modules,reader,semen,utils
+%.link: %.o
+%.import.scm: %.o
+%.o: %.scm
+	$(CHICKEN_C) $(CSC_FLAGS) $< -e -c -J -o $@ -link $(@:%.o=%)
 
-sex-tests:
-	$(MAKE) -C tests sex-tests
-	cp ./tests/sex-tests ./
+
+sex-tests: $(OBJ) tests/*.scm
+	cd ./tests && $(CHICKEN_C) $(CSC_FLAGS) run.scm -c -o sex-tests.o
+	$(CHICKEN_C) $(CSC_FLAGS) $(OBJ) ./tests/sex-tests.o -o sex-tests
 
 clean:
-	rm -f $(OBJ) main.o
-	rm -f *.import.scm
-	rm -f *.link
+	rm -f $(OBJ) main.o ./tests/sex-tests.o
+	rm -f $(IMPORTS)
+	rm -f $(LINK) main.link
 	rm -f sexc sex-tests

fmt-c-writer.module.scm

@@ -1,3 +0,0 @@
-(module fmt-c-writer (emit-c
-                      sex-fmt-current-file)
-  "fmt-c-writer.scm")

fmt-c-writer.scm

@@ -1,5 +1,7 @@
 ;;; Sex fmt-c output writer
 
+(module fmt-c-writer (emit-c
+                      sex-fmt-current-file)
   (import
     scheme
     (chicken base)
@@ -280,4 +282,4 @@
                     (sex-fmt-line-num start-line)
                     (fmt #t (line-directive-string) nl)))
                 (fmt #t (c-expr (process-toplevel-form form)) nl))
-            sex-forms))
+              sex-forms)))

macros.scm

@@ -0,0 +1,45 @@
+(module macros
+    (register-macro
+     cat
+     get-macro
+     macro?
+     apply-macro
+     defmacro)
+  (import
+    scheme
+    (only fmt fmt)
+    (chicken base)
+    (chicken plist)
+    (chicken string))
+
+  (define (cat-syms s-1 s-2)
+    (fmt #f s-1 s-2))
+
+  (define (cat sym-1 sym-2)
+    (string->symbol (cat-syms sym-1 sym-2)))
+
+  (define (register-macro name arglist body)
+    (put! name 'sex-macro
+          `(lambda ,arglist
+             (import scheme
+                     (only macros cat))
+             ,@body)))
+
+  (define (get-macro name)
+    (eval (get name 'sex-macro)))
+
+  (define (macro? form)
+    (and (list? form)
+         (symbol? (car form))
+         (get (car form) 'sex-macro)))
+
+  (define (apply-macro form)
+    (assert (macro? form)
+            (fmt #f (car form) " is not a macro"))
+    (apply (get-macro (car form))
+           (cdr form)))
+
+  (define (defmacro form)
+    (let ((arglist (car form))
+          (body (cdr form)))
+      (register-macro (car arglist) (cdr arglist) body))))

module-system.scm

@@ -0,0 +1,92 @@
+(module module-system
+    (get-modules-public-forms
+     load-persistent-module-paths
+     read-public-interface)
+
+  (import
+    scheme
+    brev-separate
+    (chicken base)
+    (chicken file)
+    (chicken load)
+    (chicken pathname)
+    (chicken process-context)
+    (chicken string)
+    fmt
+    reader
+    srfi-1
+    utils)
+
+  (define +persistent-module-paths+ (list))
+
+  (define (get-modules-public-forms module-list)
+    ;; Module list is a list of symbols
+    ;; How Sex handles modules:
+    ;; For each module in a list, construct path, find module by path in
+    ;; module path directories, extract public definitions from the
+    ;; module, paste them in current one in emulation of C include
+    ;; directives.
+    (fold-right append (list)
+                (map (fn (import-module (symbol->string x)))
+                     module-list)))
+
+  (define (import-module name)
+    (let ((module-path (locate-module name)))
+      (assert module-path (fmt #f "Failed to find module " name " in "
+                               (get-module-paths)))
+      (read-public-interface module-path)))
+
+  (define (get-module-paths)
+    (cons (current-directory)
+          +persistent-module-paths+))
+
+  (define (locate-module name)
+    ;; Module locations: relative to file being compiled, or in what was
+    ;; in SEX_MODULE_PATH env var at the start of the process (see
+    ;; load-persistent-module-paths function)
+
+    (let ((search-paths (get-module-paths)))
+      (let loop ((paths search-paths))
+        (if (null? paths)
+            #f
+            (or (module-exists? name (car paths))
+                (loop (cdr paths)))))))
+
+  (define (module-exists? name module-dir)
+    ;; returns absolute path to module, if it exists
+    (and (directory-exists? module-dir)
+         (let ((module-path (make-absolute-pathname module-dir name "sex")))
+           (and (file-exists? module-path)
+                (file-readable? module-path)
+                module-path))))
+
+  (define (read-public-interface module-path)
+    ;; pub fns are reduced to prototypes, other pub forms are just pasted
+    (let ((raw-forms (read-from-file module-path)))
+      (fold
+       process-public-interface-form
+       (list)
+       raw-forms)))
+
+;;; TODO: use semen facilities to analyze modules
+  (define (process-public-interface-form form acc)
+    (case (car form)
+      ((pub)
+       (case (cadr form)
+         ((fn)                 ; replace with prototype
+          ;; fn type name (arg-list) (body)
+          ;; 1    2   3       4 - we need first 4
+          (cons (take (cdr form) 4) acc))
+         ((define defmacro import include struct typedef union var)
+          (cons (cdr form) acc))
+         (else (error "Pub what? " (cadr form)))))
+      (else acc)))
+
+  (define (load-persistent-module-paths)
+    (let ((sex-module-path-env-var
+           (get-env-var "SEX_MODULE_PATH")))
+      (when sex-module-path-env-var
+        (set! +persistent-module-paths+
+          (map (lambda (p)
+                 (make-absolute-pathname p #f #f))
+               (string-split sex-module-path-env-var ":")))))))

reader.module.scm

@@ -1,3 +0,0 @@
-(module reader (read-from-file
-                read-raw-forms)
-  "reader.scm")

reader.scm

@@ -1,3 +1,5 @@
+(module reader (read-from-file
+                read-raw-forms)
   (import
     scheme
     (chicken base)
@@ -59,4 +61,4 @@
                      (cons r acc)))))))
     (if (eq? input-source 'stdin)
         (read-forms (list))
-      (read-from-file input-source)))
+        (read-from-file input-source))))

semen.module.scm

@@ -1,2 +0,0 @@
-(module semen ()
-  "semen.scm")

semen.scm

@@ -1,5 +1,6 @@
 ;;; Sex semantic engine
 
+(module semen ()
   (import
     scheme
     (chicken base)
@@ -7,9 +8,9 @@
     (chicken string)
     (chicken module)
     fmt
-  sex-macros
-  sex-modules
+    macros
     matchable                         ; pattern matching
+    module-system
     srfi-1                            ; list routines
     srfi-69                           ; hash tables
     utils
@@ -237,3 +238,4 @@ Returns #f if the form is not a function, returns the form otherwise"
     (if (sex-fn-public? fn-form)
         (drop fn-form 5)
         (drop fn-form 4)))
+  )

sex-fmt-c.scm

@@ -112,7 +112,7 @@
     (lambda (st)
       ((fmt-let 'op op
                 (if (and (c-op<= (fmt-op st) op)
-                         (not (vector? x)))
+                         (not (vector? st)))
                     (c-paren x)
                     x))
        st)))

sex-macros.module.scm

@@ -1,8 +0,0 @@
-(module sex-macros
-    (register-macro
-     cat
-     get-macro
-     macro?
-     apply-macro
-     defmacro)
-  "sex-macros.scm")

sex-macros.scm

@@ -1,38 +0,0 @@
-(import
-  scheme
-  (only fmt fmt)
-  (chicken base)
-  (chicken plist)
-  (chicken string))
-
-(define (cat-syms s-1 s-2)
-  (fmt #f s-1 s-2))
-
-(define (cat sym-1 sym-2)
-  (string->symbol (cat-syms sym-1 sym-2)))
-
-(define (register-macro name arglist body)
-  (put! name 'sex-macro
-        `(lambda ,arglist
-           (import scheme
-                   (only sex-macros cat))
-           ,@body)))
-
-(define (get-macro name)
-  (eval (get name 'sex-macro)))
-
-(define (macro? form)
-  (and (list? form)
-       (symbol? (car form))
-       (get (car form) 'sex-macro)))
-
-(define (apply-macro form)
-  (assert (macro? form)
-          (fmt #f (car form) " is not a macro"))
-  (apply (get-macro (car form))
-         (cdr form)))
-
-(define (defmacro form)
-  (let ((arglist (car form))
-        (body (cdr form)))
-    (register-macro (car arglist) (cdr arglist) body)))

sex-mode.el

@@ -51,9 +51,7 @@ All commands in `lisp-mode-shared-map' are inherited by this map.")
      ;; Keywords
      (list (concat "("
                    (regexp-opt '(
-                                 "begin"
                                  "case"
-                                 "default"
                                  "do"
                                  "if"
                                  "for"
@@ -85,8 +83,6 @@ All commands in `lisp-mode-shared-map' are inherited by this map.")
 (put 'union 'lisp-indent-function 'defun)
 (put 'var 'lisp-indent-function 0)
 (put 'import 'lisp-indent-function 1)
-(put 'switch 'lisp-indent-function 1)
-(put 'case 'lisp-indent-function 1)
 
 ;;;###autoload
 (define-derived-mode sex-mode lisp-data-mode "Sex"

sex-modules.module.scm

@@ -1,5 +0,0 @@
-(module sex-modules
-    (get-modules-public-forms
-     load-persistent-module-paths
-     read-public-interface)
-  "sex-modules.scm")

sex-modules.scm

@@ -1,87 +0,0 @@
-(import
-  scheme
-  brev-separate
-  (chicken base)
-  (chicken file)
-  (chicken load)
-  (chicken pathname)
-  (chicken process-context)
-  (chicken string)
-  fmt
-  reader
-  srfi-1
-  utils)
-
-(define +persistent-module-paths+ (list))
-
-(define (get-modules-public-forms module-list)
-  ;; Module list is a list of symbols
-  ;; How Sex handles modules:
-  ;; For each module in a list, construct path, find module by path in
-  ;; module path directories, extract public definitions from the
-  ;; module, paste them in current one in emulation of C include
-  ;; directives.
-  (fold-right append (list)
-              (map (fn (import-module (symbol->string x)))
-                   module-list)))
-
-(define (import-module name)
-  (let ((module-path (locate-module name)))
-    (assert module-path (fmt #f "Failed to find module " name " in "
-                             (get-module-paths)))
-    (read-public-interface module-path)))
-
-(define (get-module-paths)
-  (cons (current-directory)
-        +persistent-module-paths+))
-
-(define (locate-module name)
-  ;; Module locations: relative to file being compiled, or in what was
-  ;; in SEX_MODULE_PATH env var at the start of the process (see
-  ;; load-persistent-module-paths function)
-
-  (let ((search-paths (get-module-paths)))
-    (let loop ((paths search-paths))
-      (if (null? paths)
-          #f
-          (or (module-exists? name (car paths))
-              (loop (cdr paths)))))))
-
-(define (module-exists? name module-dir)
-  ;; returns absolute path to module, if it exists
-  (and (directory-exists? module-dir)
-       (let ((module-path (make-absolute-pathname module-dir name "sex")))
-         (and (file-exists? module-path)
-              (file-readable? module-path)
-              module-path))))
-
-(define (read-public-interface module-path)
-  ;; pub fns are reduced to prototypes, other pub forms are just pasted
-  (let ((raw-forms (read-from-file module-path)))
-    (fold
-     process-public-interface-form
-     (list)
-     raw-forms)))
-
-;;; TODO: use semen facilities to analyze modules
-(define (process-public-interface-form form acc)
-  (case (car form)
-    ((pub)
-     (case (cadr form)
-       ((fn)                 ; replace with prototype
-        ;; fn type name (arg-list) (body)
-        ;; 1    2   3       4 - we need first 4
-        (cons (take (cdr form) 4) acc))
-       ((define defmacro import include struct typedef union var)
-        (cons (cdr form) acc))
-       (else (error "Pub what? " (cadr form)))))
-    (else acc)))
-
-(define (load-persistent-module-paths)
-  (let ((sex-module-path-env-var
-         (get-env-var "SEX_MODULE_PATH")))
-    (when sex-module-path-env-var
-      (set! +persistent-module-paths+
-        (map (lambda (p)
-               (make-absolute-pathname p #f #f))
-             (string-split sex-module-path-env-var ":"))))))

sexc.module.scm

@@ -1 +0,0 @@
-(module sexc (main) "sexc.scm")

sexc.scm

@@ -1,3 +1,4 @@
+(module sexc (main)
   (import scheme
           brev-separate
           (chicken base)
@@ -10,8 +11,8 @@
           fmt
           fmt-c-writer
           getopt-long
-        sex-macros
-        sex-modules
+          macros
+          module-system
           reader
           semen
           srfi-1                          ; list routines
@@ -163,4 +164,4 @@
                ;; Emit processed and macro-expanded sex code, or emit C code
                (emit-c-or-sex sex-forms output args)
                ;; Compile file!
-             (compile-to-file sex-forms output args)))))))
+               (compile-to-file sex-forms output args))))))))

tests/Makefile

@@ -1,45 +1 @@
-CHICKEN_C = csc
 
-CSC_FLAGS += -K prefix -static
-MODULE_FLAGS = -emit-all-import-libraries -module-registration -c
-
-MODULES = utils sex-macros reader sex-modules semen sex-fmt-c fmt-c-writer sexc
-SEX_OBJ = $(MODULES:%=%.o)
-
-TESTS = basic semen reader fmt-c-writer utils
-TEST_SRCS = $(TESTS:%=%.scm)
-
-sex-tests: run.scm $(TEST_SRCS) $(SEX_OBJ)
-	$(CHICKEN_C) $(CSC_FLAGS) run.scm -o sex-tests -link sexc
-
-#------------------------------------------------------------------
-
-utils.o: utils.module.scm ../utils.scm
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) utils.module.scm -o utils.o -unit utils
-
-sex-macros.o: sex-macros.module.scm ../sex-macros.scm
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) sex-macros.module.scm -o sex-macros.o -unit sex-macros
-
-reader.o: reader.module.scm ../reader.scm
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) reader.module.scm -o reader.o -unit reader
-
-sex-modules.o: sex-modules.module.scm ../sex-modules.scm reader.o utils.o
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) sex-modules.module.scm -o sex-modules.o -unit sex-modules -link reader,utils
-
-semen.o: semen.module.scm ../semen.scm sex-macros.o sex-modules.o utils.o
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) semen.module.scm -o semen.o -unit semen -link sex-macros,sex-modules,utils
-
-sex-fmt-c.o: ../sex-fmt-c.scm
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) ../sex-fmt-c.scm -o sex-fmt-c.o -unit sex-fmt-c
-
-fmt-c-writer.o: fmt-c-writer.module.scm ../fmt-c-writer.scm sex-fmt-c.o utils.o
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) fmt-c-writer.module.scm -o fmt-c-writer.o -unit fmt-c-writer -link sex-fmt-c,utils
-
-sexc.o: sexc.module.scm ../sexc.scm fmt-c-writer.o sex-macros.o sex-modules.o reader.o semen.o utils.o
-	$(CHICKEN_C) $(CSC_FLAGS) $(MODULE_FLAGS) sexc.module.scm -o sexc.o -unit sexc -link fmt-c-writer,sex-macros,sex-modules,reader,semen,utils
-
-clean:
-	rm -f $(OBJ)
-	rm -f *.import.scm
-	rm -f *.link
-	rm -f sex-tests

tests/basic.scm

@@ -1,5 +1,3 @@
-(import fmt-c-writer)
-
 (test-group "basic"
 
   ;; unkebabify

tests/fmt-c-writer.module.scm

@@ -1,3 +0,0 @@
-(module fmt-c-writer
-    *
-  "../fmt-c-writer.scm")

tests/reader.module.scm

@@ -1,3 +0,0 @@
-(module reader
-    *
-  "../reader.scm")

tests/reader.scm

@@ -1,5 +1,4 @@
-(import (chicken port)
-        reader)
+(import (chicken port))
 
 (define-syntax reader-test
   (syntax-rules ()

tests/run.scm

@@ -1,4 +1,10 @@
+(declare (uses fmt-c-writer
+               semen))
+
 (import
+  (chicken process)
+  (chicken process-context)
+  srfi-1
   test)
 
 (include "basic.scm")

tests/semen.module.scm

@@ -1,2 +0,0 @@
-(module semen *
-  "../semen.scm")

tests/semen.scm

@@ -1,5 +1,4 @@
-(import srfi-69
-        semen)
+(import srfi-69)
 
 (define print-str-fn
   '(fn void print-str ((string s))
@@ -39,11 +38,11 @@
   (define (form-identity form env)
     form)
 
-  (test 'a (walk-form 'a form-identity (make-hash-table)))
-  (test '(a b c) (walk-form '(a b c) form-identity (make-hash-table)))
+  (test 'a (semen-walk-form 'a form-identity (make-hash-table)))
+  (test '(a b c) (semen-walk-form '(a b c) form-identity (make-hash-table)))
 
-  (test 'a (macro-expand 'a))
-  (test '(a b c) (macro-expand '(a b c)))
+  (test 'a (semen-macro-expand 'a))
+  (test '(a b c) (semen-macro-expand '(a b c)))
 
   (let ((sex-code-macro
          '((defmacro (x10 a)

tests/sex-macros.module.scm

@@ -1,3 +0,0 @@
-(module sex-macros
-    *
-  "../sex-macros.scm")

tests/sex-modules.module.scm

@@ -1,3 +0,0 @@
-(module sex-modules
-    *
-  "../sex-modules.scm")

tests/sexc.module.scm

@@ -1 +0,0 @@
-(module sexc (main) "../sexc.scm")

tests/utils.module.scm

@@ -1,3 +0,0 @@
-(module utils
-    *
-  "../utils.scm")

tests/utils.scm

@@ -1,5 +1,3 @@
-(import utils)
-
 (test-group "utils"
 
   (test

utils.module.scm

@@ -1,10 +0,0 @@
-(module utils
-    (get-env-var
-     set-working-directory
-     to-absolute-pathname
-     list-split
-     list-join
-     recons
-     with-directory
-     )
-  "utils.scm")

utils.scm

@@ -1,3 +1,13 @@
+(module utils
+    (get-env-var
+     set-working-directory
+     to-absolute-pathname
+     list-split
+     list-join
+     recons
+     with-directory
+     )
+
   (import
     scheme
     (chicken base)
@@ -64,3 +74,4 @@
              (eq? new-cdr (cdr old-cons)))
         old-cons
         (cons new-car new-cdr)))
+  )