diff --git a/src/main.lisp b/src/main.lisp
index 1336cb4..ffd704a 100644
--- a/src/main.lisp
+++ b/src/main.lisp
@@ -47,7 +47,7 @@
   (declare (type string value))
   (substitute-if #\_ #'is-forbidden-character-p value))
 
-; (declaim (ftype (function (string symbol null) string) value->safe-string))
+(declaim (ftype (function (atom) string) value->safe-string))
 (defun value->safe-string (value)
   (protect-file-system (typecase value
             (string value)
@@ -65,6 +65,7 @@
 
 ; db/new ensures directory '<path>/data/' exist,
 ; then loads values from existing files, if any, and puts them into db-data.
+(declaim (ftype (function (string) db) db/new))
 (defun db/new (path)
   (declare (type string path))
   (let ((data          (make-hash-table))
@@ -99,6 +100,7 @@
   (concatenate 'string dbpath "/partitions/by_" name "/" object-attribute "/"))
 
 ; Example: "./storage/cars/" "name" #'vehicle-name object -> "./storage/cars/indexes/by_name/Corvet".
+(declaim (ftype (function (string string function atom) string) db/index/get-symlink-path))
 (defun db/index/get-symlink-path (dbpath index-name fsymbol object)
   (declare (type string dbpath index-name))
   (declare (type function fsymbol))
@@ -112,6 +114,7 @@
 ;   -> (osicat:make-link "./storage/cars/indexes/by_name/Corvet"
 ;          :target "../../data/0000000015"
 ;          :hard nil)
+(declaim (ftype (function (string string function atom string) null) db/index/new))
 (defun db/index/new (dbpath index-name fsymbol object file-name)
   (declare (type string dbpath index-name file-name))
   (declare (type function fsymbol))
@@ -121,15 +124,19 @@
     ; works even when the database directory is moved
     (osicat:make-link symlink-path
       :target (concatenate 'string "../../data/" file-name)
-      :hard nil)))
+      :hard nil))
+  (values nil))
 
+(declaim (ftype (function (string string function atom) null) db/index/del))
 (defun db/index/del (dbpath index-name fsymbol object)
   (declare (type string dbpath index-name))
   (declare (type function fsymbol))
-  (delete-file (db/index/get-symlink-path dbpath index-name fsymbol object)))
+  (delete-file (db/index/get-symlink-path dbpath index-name fsymbol object))
+  (values nil))
 
 ; Example: "./storage/cars/" "color" #'vehicle-color object "0000000015".
 ;   -> "./storage/cars/partitions/by_color/Red/0000000015".
+(declaim (ftype (function (string string function atom string) string) db/partition/get-symlink-path))
 (defun db/partition/get-symlink-path (dbpath partition-name fsymbol object file-name)
   (declare (type string dbpath partition-name file-name))
   (declare (type function fsymbol))
@@ -143,6 +150,7 @@
 ;   -> (osicat:make-link "./storage/cars/partitions/by_color/Red/0000000015"
 ;          :target "../../../data/0000000015"
 ;          :hard nil)
+(declaim (ftype (function (string string function atom string) null) db/partition/new))
 (defun db/partition/new (dbpath partition-name fsymbol object file-name)
   (declare (type string dbpath partition-name file-name))
   (declare (type function fsymbol))
@@ -154,14 +162,19 @@
     ; works even when the database directory is moved
     (osicat:make-link symlink-path
       :target (concatenate 'string "../../../data/" file-name)
-      :hard nil)))
+      :hard nil))
+  (values nil))
 
+(declaim (ftype (function (string string function atom string) null) db/partition/del))
 (defun db/partition/del (dbpath partition-name fsymbol object file-basename)
   (declare (type string dbpath partition-name file-basename))
   (declare (type function fsymbol))
-  (delete-file (db/partition/get-symlink-path dbpath partition-name fsymbol object file-basename)))
+  (delete-file (db/partition/get-symlink-path dbpath partition-name fsymbol object file-basename))
+  (values nil))
 
+(declaim (ftype (function (db string function) null) db/new-index))
 (defun db/new-index (database index-name fsymbol)
+  (declare (type db database))
   (declare (type string index-name))
   (declare (type function fsymbol))
   (let ((dbpath (db-path database))
@@ -178,8 +191,10 @@
         (handler-case (db/index/new dbpath index-name fsymbol object (number->filename number))
           (OSICAT-POSIX:EEXIST ()
             (format t "dodb:db/new-index: symlink already exists, ignoring.~&"))))
-      (db-data database))))
+      (db-data database)))
+  (values nil))
 
+(declaim (ftype (function (string string function atom string atom) null) db/partition/update))
 (defun db/partition/update (dbpath partition-name fsymbol object file-name old-object)
   (declare (type string dbpath partition-name file-name))
   (declare (type function fsymbol))
@@ -192,7 +207,9 @@
         ; create new partition
         (db/partition/new dbpath partition-name fsymbol     object file-name)))))
 
+(declaim (ftype (function (db string function) null) db/new-partition))
 (defun db/new-partition (database partition-name fsymbol)
+  (declare (type db database))
   (declare (type string partition-name))
   (declare (type function fsymbol))
   (let ((dbpath         (db-path database))
@@ -209,7 +226,8 @@
         (handler-case (db/partition/new dbpath partition-name fsymbol object (number->filename number))
           (OSICAT-POSIX:EEXIST ()
             (format t "dodb:db/new-partition: symlink already exists, ignoring.~&"))))
-      (db-data database))))
+      (db-data database)))
+    (values nil))
 
 ; Example: "./storage/cars/data/000000000000018".
 (declaim (ftype (function (string string) string) get-filepath))
@@ -217,7 +235,9 @@
   (declare (type string dbpath file-name))
   (concatenate 'string dbpath "/data/" file-name))
 
+(declaim (ftype (function (db atom) integer) db/add))
 (defun db/add (database object)
+  (declare (type db database))
   (incf (db-current-index database))
   (let* ((file-basename     (number->filename (db-current-index database)))
          (dbpath            (db-path database))
@@ -245,7 +265,9 @@
   (setf (gethash (db-current-index database) (db-data database)) object)
   (db-current-index database))
 
+(declaim (ftype (function (db integer) null) db/del))
 (defun db/del (database object-index)
+  (declare (type db database))
   (declare (type integer object-index))
   (let ((file-basename (number->filename object-index))
         (dbpath        (db-path database))
@@ -264,10 +286,13 @@
       (db-partitions database))
 
     ; remove in-memory data
-    (remhash object-index (db-data database))))
+    (remhash object-index (db-data database)))
+  (values nil))
 
 ; Search for the data from the FS.
+(declaim (ftype (function (db string atom) integer) db/get-by-index))
 (defun db/get-by-index (database index-name attribute-value)
+  (declare (type db database))
   (declare (type string index-name))
   (let ((value (value->safe-string attribute-value)))
     (filename->integer
@@ -276,13 +301,16 @@
           (db/index/get-directory-path (db-path database) index-name) "/" value)))))
 
 ; Search for the data from the FS.
+(declaim (ftype (function (db string atom) cons) db/get-by-partition))
 (defun db/get-by-partition (database name attribute-value)
+  (declare (type db database))
   (declare (type string name))
   (let ((value (value->safe-string attribute-value))
         (dbpath (db-path database)))
     (loop for filename in (osicat:list-directory (db/partition/get-directory-path dbpath name value))
           collect (filename->integer filename))))
 
+(declaim (ftype (function (string string function atom string atom) null) db/index/update))
 (defun db/index/update (dbpath index-name fsymbol object file-name old-object)
   (declare (type string dbpath index-name file-name))
   (declare (type function fsymbol))
@@ -301,7 +329,9 @@
 
 ; TODO: check database integrity (redundancy)
 ; TODO: locking
+(declaim (ftype (function (db integer) null) db/update))
 (defun db/update (database object-index)
+  (declare (type db database))
   (declare (type integer object-index))
   (let* ((object            (gethash object-index (db-data database)))
          (dbpath            (db-path database))
@@ -327,8 +357,12 @@
     ; handle partitions
     (maphash #'(lambda (partition-name fsymbol)
         (db/partition/update dbpath partition-name fsymbol object file-basename old-object))
-      (db-partitions database))))
+      (db-partitions database)))
+  (values nil))
 
+(declaim (ftype (function (db) null) db/drop-everything))
 (defun db/drop-everything (database)
+  (declare (type db database))
   (osicat:delete-directory-and-files (db-path database))
-  (clrhash (db-data database)))
+  (clrhash (db-data database))
+  (values nil))