3 files changed, 709 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index ecf60222672..89528690e40 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -487,6 +487,11 @@ The seq library adds sequence manipulation functions and macros that
 complement basic functions provided by subr.el. All functions are
 prefixed with `seq-' and work on lists, strings and vectors.
 
+** map
+*** New map library:
+The map library provides map-manipulation functions that work on alists,
+hash-table and arrays.  All functions are prefixed with "map-".
+
 ** Calendar and diary
 
 +++
diff --git a/lisp/emacs-lisp/map.el b/lisp/emacs-lisp/map.el
new file mode 100644
index 00000000000..46c795840b0
--- /dev/null
+++ b/lisp/emacs-lisp/map.el
@@ -0,0 +1,371 @@
+;;; map.el --- Map manipulation functions  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2015 Free Software Foundation, Inc.
+
+;; Author: Nicolas Petton <nicolas@petton.fr>
+;; Keywords: convenience, map, hash-table, alist, array
+;; Version: 1.0
+;; Package: map
+
+;; Maintainer: emacs-devel@gnu.org
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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.
+
+;; GNU Emacs 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; map.el provides map-manipulation functions that work on alists,
+;; hash-table and arrays.  All functions are prefixed with "map-".
+;;
+;; Functions taking a predicate or iterating over a map using a
+;; function take the function as their first argument.  All other
+;; functions take the map as their first argument.
+
+;; TODO:
+;; - Add support for char-tables
+;; - Maybe add support for gv?
+;; - See if we can integrate text-properties
+;; - A macro similar to let-alist but working on any type of map could
+;;   be really useful
+
+;;; Code:
+
+(require 'seq)
+
+(pcase-defmacro map (&rest args)
+  "pcase pattern matching map elements.
+Matches if the object is a map (list, hash-table or array), and
+binds values from ARGS to the corresponding element of the map.
+
+ARGS can be a list elements of the form (KEY . PAT) or elements
+of the form SYMBOL, which stands for (SYMBOL . SYMBOL)."
+  `(and (pred map-p)
+        ,@(map--make-pcase-bindings args)))
+
+(defmacro map-let (args map &rest body)
+  "Bind the variables in ARGS to the elements of MAP then evaluate BODY.
+
+ARGS can be an alist of key/binding pairs or a list of keys.  MAP
+can be a list, hash-table or array."
+  (declare (indent 2) (debug t))
+  `(pcase-let ((,(map--make-pcase-patterns args) ,map))
+     ,@body))
+
+(defun map-elt (map key &optional default)
+  "Perform a lookup in MAP of KEY and return its associated value.
+If KEY is not found, return DEFAULT which defaults to nil.
+
+If MAP is a list, `equal' is used to lookup KEY.
+
+MAP can be a list, hash-table or array."
+  (map--dispatch map
+    :list (map--elt-list map key default)
+    :hash-table (gethash key map default)
+    :array (map--elt-array map key default)))
+
+(defmacro map-put (map key value)
+  "In MAP, associate KEY with VALUE and return MAP.
+If KEY is already present in MAP, replace the associated value
+with VALUE.
+
+MAP can be a list, hash-table or array."
+  (declare (debug t))
+  `(progn
+     (map--dispatch (m ,map m)
+       :list (setq ,map (cons (cons ,key ,value) m))
+       :hash-table (puthash ,key ,value m)
+       :array (aset m ,key ,value))))
+
+(defmacro map-delete (map key)
+  "In MAP, delete the key KEY if present and return MAP.
+If MAP is an array, store nil at the index KEY.
+
+MAP can be a list, hash-table or array."
+  (declare (debug t))
+  `(progn
+     (map--dispatch (m ,map m)
+       :list (setq ,map (map--delete-alist m ,key))
+       :hash-table (remhash ,key m)
+       :array (map--delete-array m ,key))))
+
+(defun map-nested-elt (map keys &optional default)
+  "Traverse MAP using KEYS and return the looked up value or DEFAULT if nil.
+
+Map can be a nested map composed of alists, hash-tables and arrays."
+  (or (seq-reduce (lambda (acc key)
+                    (when (map-p acc)
+                      (map-elt acc key)))
+                  keys
+                  map)
+      default))
+
+(defun map-keys (map)
+  "Return the list of keys in MAP.
+
+MAP can be a list, hash-table or array."
+  (map-apply (lambda (key _) key) map))
+
+(defun map-values (map)
+  "Return the list of values in MAP.
+
+MAP can be a list, hash-table or array."
+  (map-apply (lambda (_ value) value) map))
+
+(defun map-pairs (map)
+  "Return the elements of MAP as key/value association lists.
+
+MAP can be a list, hash-table or array."
+  (map-apply #'cons map))
+
+(defun map-length (map)
+  "Return the length of MAP.
+
+MAP can be a list, hash-table or array."
+  (length (map-keys map)))
+
+(defun map-copy (map)
+  "Return a copy of MAP.
+
+MAP can be a list, hash-table or array."
+  (map--dispatch map
+    :list (seq-copy map)
+    :hash-table (copy-hash-table map)
+    :array (seq-copy map)))
+
+(defun map-apply (function map)
+  "Apply FUNCTION to each element of MAP and return the result as a list.
+FUNCTION is called with two arguments, the key and the value.
+
+MAP can be a list, hash-table or array."
+  (funcall (map--dispatch map
+             :list #'map--apply-alist
+             :hash-table #'map--apply-hash-table
+             :array #'map--apply-array)
+           function
+           map))
+
+(defun map-keys-apply (function map)
+  "Return the result of applying FUNCTION to each key of MAP.
+
+MAP can be a list, hash-table or array."
+  (map-apply (lambda (key _)
+               (funcall function key))
+             map))
+
+(defun map-values-apply (function map)
+  "Return the result of applying FUNCTION to each value of MAP.
+
+MAP can be a list, hash-table or array."
+  (map-apply (lambda (_ val)
+               (funcall function val))
+             map))
+
+(defun map-filter (pred map)
+  "Return an alist of the key/val pairs for which (PRED key val) is non-nil in MAP.
+
+MAP can be a list, hash-table or array."
+  (delq nil (map-apply (lambda (key val)
+                         (if (funcall pred key val)
+                             (cons key val)
+                           nil))
+                       map)))
+
+(defun map-remove (pred map)
+  "Return an alist of the key/val pairs for which (PRED key val) is nil in MAP.
+
+MAP can be a list, hash-table or array."
+  (map-filter (lambda (key val) (not (funcall pred key val)))
+              map))
+
+(defun map-p (map)
+  "Return non-nil if MAP is a map (list, hash-table or array)."
+  (or (listp map)
+      (hash-table-p map)
+      (arrayp map)))
+
+(defun map-empty-p (map)
+  "Return non-nil is MAP is empty.
+
+MAP can be a list, hash-table or array."
+  (map--dispatch map
+    :list (null map)
+    :array (seq-empty-p map)
+    :hash-table (zerop (hash-table-count map))))
+
+(defun map-contains-key-p (map key &optional testfn)
+  "Return non-nil if MAP contain the key KEY, nil otherwise.
+Equality is defined by TESTFN if non-nil or by `equal' if nil.
+
+MAP can be a list, hash-table or array."
+  (seq-contains-p (map-keys map) key testfn))
+
+(defun map-some-p (pred map)
+  "Return a key/value pair for which (PRED key val) is non-nil in MAP.
+
+MAP can be a list, hash-table or array."
+  (catch 'map--break
+    (map-apply (lambda (key value)
+                 (when (funcall pred key value)
+                   (throw 'map--break (cons key value))))
+               map)
+    nil))
+
+(defun map-every-p (pred map)
+  "Return non-nil if (PRED key val) is non-nil for all elements of the map MAP.
+
+MAP can be a list, hash-table or array."
+  (catch 'map--break
+    (map-apply (lambda (key value)
+                 (or (funcall pred key value)
+                     (throw 'map--break nil)))
+               map)
+    t))
+
+(defun map-merge (type &rest maps)
+  "Merge into a map of type TYPE all the key/value pairs in the maps MAPS.
+
+MAP can be a list, hash-table or array."
+  (let (result)
+    (while maps
+      (map-apply (lambda (key value)
+                   (map-put result key value))
+                 (pop maps)))
+    (map-into result type)))
+
+(defun map-into (map type)
+  "Convert the map MAP into a map of type TYPE.
+
+TYPE can be one of the following symbols: list or hash-table.
+MAP can be a list, hash-table or array."
+  (pcase type
+    (`list (map-pairs map))
+    (`hash-table (map--into-hash-table map))
+    (t (error "Not a map type name: %S" type))))
+
+(defmacro map--dispatch (spec &rest args)
+  "Evaluate one of the provided forms depending on the type of MAP.
+
+SPEC can be a map or a list of the form (VAR MAP [RESULT]).
+ARGS should have the form [TYPE FORM]...
+
+The following keyword types are meaningful: `:list',
+`:hash-table' and `array'.
+
+An error is thrown if MAP is neither a list, hash-table nor array.
+
+Return RESULT if non-nil or the result of evaluation of the
+form.
+
+\(fn (VAR MAP [RESULT]) &rest ARGS)"
+  (declare (debug t) (indent 1))
+  (unless (listp spec)
+    (setq spec `(,spec ,spec)))
+  (let ((map-var (car spec))
+        (result-var (make-symbol "result")))
+    `(let ((,map-var ,(cadr spec))
+           ,result-var)
+       (setq ,result-var
+             (cond ((listp ,map-var) ,(plist-get args :list))
+                   ((hash-table-p ,map-var) ,(plist-get args :hash-table))
+                   ((arrayp ,map-var) ,(plist-get args :array))
+                   (t (error "Unsupported map: %s" ,map-var))))
+       ,@(when (cddr spec)
+          `((setq ,result-var ,@(cddr spec))))
+       ,result-var)))
+
+(defun map--apply-alist (function map)
+  "Private function used to apply FUNCTION over MAP, MAP being an alist."
+  (seq-map (lambda (pair)
+             (funcall function
+                      (car pair)
+                      (cdr pair)))
+           map))
+
+(defun map--apply-hash-table (function map)
+  "Private function used to apply FUNCTION over MAP, MAP being a hash-table."
+  (let (result)
+    (maphash (lambda (key value)
+               (push (funcall function key value) result))
+             map)
+    (nreverse result)))
+
+(defun map--apply-array (function map)
+  "Private function used to apply FUNCTION over MAP, MAP being an array."
+   (let ((index 0))
+     (seq-map (lambda (elt)
+                (prog1
+                    (funcall function index elt)
+                  (setq index (1+ index))))
+              map)))
+
+(defun map--elt-list (map key &optional default)
+  "Lookup, in the list MAP, the value associated with KEY and return it.
+If KEY is not found, return DEFAULT which defaults to nil."
+  (let ((pair (assoc key map)))
+    (if pair
+        (cdr pair)
+      default)))
+
+(defun map--elt-array (map key &optional default)
+  "Return the element of the array MAP at the index KEY.
+If KEY is not found, return DEFAULT which defaults to nil."
+  (let ((len (seq-length map)))
+    (or (and (>= key 0)
+             (<= key len)
+             (seq-elt map key))
+        default)))
+
+(defun map--delete-alist (map key)
+  "Return MAP with KEY removed."
+  (seq-remove (lambda (pair)
+                (equal key (car pair)))
+              map))
+
+(defun map--delete-array (map key)
+  "Set nil in the array MAP at the index KEY if present and return MAP."
+  (let ((len (seq-length map)))
+    (and (>= key 0)
+         (<= key len)
+         (aset m key nil)))
+  map)
+
+(defun map--into-hash-table (map)
+  "Convert MAP into a hash-table."
+  (let ((ht (make-hash-table :size (map-length map)
+                             :test 'equal)))
+    (map-apply (lambda (key value)
+                 (map-put ht key value))
+               map)
+    ht))
+
+(defun map--make-pcase-bindings (args)
+  "Return a list of pcase bindings from ARGS to the elements of a map."
+  (seq-map (lambda (elt)
+             (if (consp elt)
+                 `(app (pcase--flip map-elt ',(car elt)) ,(cdr elt))
+               `(app (pcase--flip map-elt ',elt) ,elt)))
+           args))
+
+(defun map--make-pcase-patterns (args)
+  "Return a list of `(map ...)' pcase patterns built from ARGS."
+  (cons 'map
+        (seq-map (lambda (elt)
+                   (if (and (consp elt) (eq 'map (car elt)))
+                       (map--make-pcase-patterns elt)
+                     elt))
+                 args)))
+
+(provide 'map)
+;;; map.el ends here
diff --git a/test/automated/map-tests.el b/test/automated/map-tests.el
new file mode 100644
index 00000000000..2f7d4eb0572
--- /dev/null
+++ b/test/automated/map-tests.el
@@ -0,0 +1,333 @@
+;;; map-tests.el --- Tests for map.el
+
+;; Copyright (C) 2015 Free Software Foundation, Inc.
+
+;; Author: Nicolas Petton <nicolas@petton.fr>
+;; Maintainer: emacs-devel@gnu.org
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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.
+
+;; GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Tests for map.el
+
+;;; Code:
+
+(require 'ert)
+(require 'map)
+
+(defmacro with-maps-do (var &rest body)
+  "Successively bind VAR to an alist, vector and hash-table.
+Each map is built from the following alist data:
+'((0 . 3) (1 . 4) (2 . 5)).
+Evaluate BODY for each created map.
+
+\(fn (var map) body)"
+  (declare (indent 1) (debug t))
+  (let ((alist (make-symbol "alist"))
+        (vec (make-symbol "vec"))
+        (ht (make-symbol "ht")))
+   `(let ((,alist '((0 . 3)
+                    (1 . 4)
+                    (2 . 5)))
+          (,vec (make-vector 3 nil))
+          (,ht (make-hash-table)))
+      (aset ,vec 0 '3)
+      (aset ,vec 1 '4)
+      (aset ,vec 2 '5)
+      (puthash '0 3 ,ht)
+      (puthash '1 4 ,ht)
+      (puthash '2 5 ,ht)
+      (dolist (,var (list ,alist ,vec ,ht))
+        ,@body))))
+
+(ert-deftest test-map-elt ()
+  (with-maps-do map
+    (assert (= 3 (map-elt map 0)))
+    (assert (= 4 (map-elt map 1)))
+    (assert (= 5 (map-elt map 2)))
+    (assert (null (map-elt map -1)))
+    (assert (null (map-elt map 4)))))
+
+(ert-deftest test-map-elt-default ()
+  (with-maps-do map
+    (assert (= 5 (map-elt map 7 5)))))
+
+(ert-deftest test-map-elt-with-nil-value ()
+  (assert (null (map-elt '((a . 1)
+                           (b))
+                         'b
+                         '2))))
+
+(ert-deftest test-map-put ()
+  (with-maps-do map
+    (map-put map 2 'hello)
+    (assert (eq (map-elt map 2) 'hello)))
+  (let ((ht (make-hash-table)))
+    (map-put ht 2 'a)
+    (assert (eq (map-elt ht 2)
+                'a)))
+  (let ((alist '((0 . a) (1 . b) (2 . c))))
+    (map-put alist 2 'a)
+    (assert (eq (map-elt alist 2)
+                'a)))
+  (let ((vec [3 4 5]))
+   (should-error (map-put vec 3 6))))
+
+(ert-deftest test-map-put-literal ()
+  (assert (= (map-elt (map-put [1 2 3] 1 4) 1)
+             4))
+  (assert (= (map-elt (map-put (make-hash-table) 'a 2) 'a)
+             2))
+  (should-error (map-put '((a . 1)) 'b 2))
+  (should-error (map-put '() 'a 1)))
+
+(ert-deftest test-map-put-return-value ()
+  (let ((ht (make-hash-table)))
+    (assert (eq (map-put ht 'a 'hello) ht))))
+
+(ert-deftest test-map-delete ()
+  (with-maps-do map
+    (map-delete map 1)
+    (assert (null (map-elt map 1))))
+  (with-maps-do map
+    (map-delete map -2)
+    (assert (null (map-elt map -2)))))
+
+(ert-deftest test-map-delete-return-value ()
+  (let ((ht (make-hash-table)))
+    (assert (eq (map-delete ht 'a) ht))))
+
+(ert-deftest test-map-nested-elt ()
+  (let ((vec [a b [c d [e f]]]))
+    (assert (eq (map-nested-elt vec '(2 2 0)) 'e)))
+  (let ((alist '((a . 1)
+                 (b . ((c . 2)
+                       (d . 3)
+                       (e . ((f . 4)
+                             (g . 5))))))))
+    (assert (eq (map-nested-elt alist '(b e f))
+                4)))
+  (let ((ht (make-hash-table)))
+    (map-put ht 'a 1)
+    (map-put ht 'b (make-hash-table))
+    (map-put (map-elt ht 'b) 'c 2)
+    (assert (eq (map-nested-elt ht '(b c))
+                2))))
+
+(ert-deftest test-map-nested-elt-default ()
+  (let ((vec [a b [c d]]))
+    (assert (null (map-nested-elt vec '(2 3))))
+    (assert (null (map-nested-elt vec '(2 1 1))))
+    (assert (= 4 (map-nested-elt vec '(2 1 1) 4)))))
+
+(ert-deftest test-map-p ()
+  (assert (map-p nil))
+  (assert (map-p '((a . b) (c . d))))
+  (assert (map-p '(a b c d)))
+  (assert (map-p []))
+  (assert (map-p [1 2 3]))
+  (assert (map-p (make-hash-table)))
+  (assert (map-p "hello"))
+  (assert (not (map-p 1)))
+  (assert (not (map-p 'hello))))
+
+(ert-deftest test-map-keys ()
+  (with-maps-do map
+    (assert (equal (map-keys map) '(0 1 2))))
+  (assert (null (map-keys nil)))
+  (assert (null (map-keys []))))
+
+(ert-deftest test-map-values ()
+  (with-maps-do map
+    (assert (equal (map-values map) '(3 4 5)))))
+
+(ert-deftest test-map-pairs ()
+  (with-maps-do map
+    (assert (equal (map-pairs map) '((0 . 3)
+                                     (1 . 4)
+                                     (2 . 5))))))
+
+(ert-deftest test-map-length ()
+  (let ((ht (make-hash-table)))
+    (puthash 'a 1 ht)
+    (puthash 'b 2 ht)
+    (puthash 'c 3 ht)
+    (puthash 'd 4 ht)
+    (assert (= 0 (map-length nil)))
+    (assert (= 0 (map-length [])))
+    (assert (= 0 (map-length (make-hash-table))))
+    (assert (= 5 (map-length [0 1 2 3 4])))
+    (assert (= 2 (map-length '((a . 1) (b . 2)))))
+    (assert (= 4 (map-length ht)))))
+
+(ert-deftest test-map-copy ()
+  (with-maps-do map
+    (let ((copy (map-copy map)))
+      (assert (equal (map-keys map) (map-keys copy)))
+      (assert (equal (map-values map) (map-values copy)))
+      (assert (not (eq map copy))))))
+
+(ert-deftest test-map-apply ()
+  (with-maps-do map
+    (assert (equal (map-apply (lambda (k v) (cons (int-to-string k) v))
+                              map)
+                   '(("0" . 3) ("1" . 4) ("2" . 5)))))
+  (let ((vec [a b c]))
+    (assert (equal (map-apply (lambda (k v) (cons (1+ k) v))
+                              vec)
+                   '((1 . a)
+                     (2 . b)
+                     (3 . c))))))
+
+(ert-deftest test-map-keys-apply ()
+  (with-maps-do map
+    (assert (equal (map-keys-apply (lambda (k) (int-to-string k))
+                                   map)
+                   '("0" "1" "2"))))
+  (let ((vec [a b c]))
+    (assert (equal (map-keys-apply (lambda (k) (1+ k))
+                                   vec)
+                   '(1 2 3)))))
+
+(ert-deftest test-map-values-apply ()
+  (with-maps-do map
+    (assert (equal (map-values-apply (lambda (v) (1+ v))
+                                     map)
+                   '(4 5 6))))
+  (let ((vec [a b c]))
+    (assert (equal (map-values-apply (lambda (v) (symbol-name v))
+                                     vec)
+                   '("a" "b" "c")))))
+
+(ert-deftest test-map-filter ()
+  (with-maps-do map
+    (assert (equal (map-keys (map-filter (lambda (k v)
+                                           (<= 4 v))
+                                         map))
+                   '(1 2)))
+    (assert (null (map-filter (lambda (k v)
+                                (eq 'd k))
+                              map))))
+  (assert (null (map-filter (lambda (k v)
+                              (eq 3 v))
+                            [1 2 4 5])))
+  (assert (equal (map-filter (lambda (k v)
+                               (eq 3 k))
+                             [1 2 4 5])
+                 '((3 . 5)))))
+
+(ert-deftest test-map-remove ()
+  (with-maps-do map
+    (assert (equal (map-keys (map-remove (lambda (k v)
+                                           (>= v 4))
+                                         map))
+                   '(0)))
+    (assert (equal (map-keys (map-remove (lambda (k v)
+                                           (eq 'd k))
+                                         map))
+                   (map-keys map))))
+  (assert (equal (map-remove (lambda (k v)
+                               (eq 3 v))
+                             [1 2 4 5])
+                 '((0 . 1)
+                   (1 . 2)
+                   (2 . 4)
+                   (3 . 5))))
+  (assert (null (map-remove (lambda (k v)
+                              (>= k 0))
+                            [1 2 4 5]))))
+
+(ert-deftest test-map-empty-p ()
+  (assert (map-empty-p nil))
+  (assert (not (map-empty-p '((a . b) (c . d)))))
+  (assert (map-empty-p []))
+  (assert (not (map-empty-p [1 2 3])))
+  (assert (map-empty-p (make-hash-table)))
+  (assert (not (map-empty-p "hello")))
+  (assert (map-empty-p "")))
+
+(ert-deftest test-map-contains-key-p ()
+  (assert (map-contains-key-p '((a . 1) (b . 2)) 'a))
+  (assert (not (map-contains-key-p '((a . 1) (b . 2)) 'c)))
+  (assert (map-contains-key-p '(("a" . 1)) "a"))
+  (assert (not (map-contains-key-p '(("a" . 1)) "a" #'eq)))
+  (assert (map-contains-key-p [a b c] 2))
+  (assert (not (map-contains-key-p [a b c] 3))))
+
+(ert-deftest test-map-some-p ()
+  (with-maps-do map
+    (assert (equal (map-some-p (lambda (k v)
+                                 (eq 1 k))
+                               map)
+                   (cons 1 4)))
+    (assert (not (map-some-p (lambda (k v)
+                               (eq 'd k))
+                             map))))
+  (let ((vec [a b c]))
+    (assert (equal (map-some-p (lambda (k v)
+                                 (> k 1))
+                               vec)
+                   (cons 2 'c)))
+    (assert (not (map-some-p (lambda (k v)
+                               (> k 3))
+                             vec)))))
+
+(ert-deftest test-map-every-p ()
+  (with-maps-do map
+    (assert (map-every-p (lambda (k v)
+                           k)
+                         map))
+    (assert (not (map-every-p (lambda (k v)
+                                nil)
+                              map))))
+  (let ((vec [a b c]))
+    (assert (map-every-p (lambda (k v)
+                           (>= k 0))
+                         vec))
+    (assert (not (map-every-p (lambda (k v)
+                                (> k 3))
+                              vec)))))
+
+(ert-deftest test-map-into ()
+  (let* ((alist '((a . 1) (b . 2)))
+         (ht (map-into alist 'hash-table)))
+    (assert (hash-table-p ht))
+    (assert (equal (map-into (map-into alist 'hash-table) 'list)
+                   alist))
+    (assert (listp (map-into ht 'list)))
+    (assert (equal (map-keys (map-into (map-into ht 'list) 'hash-table))
+                   (map-keys ht)))
+    (assert (equal (map-values (map-into (map-into ht 'list) 'hash-table))
+                   (map-values ht)))
+    (assert (null (map-into nil 'list)))
+    (assert (map-empty-p (map-into nil 'hash-table)))
+    (should-error (map-into [1 2 3] 'string))))
+
+(ert-deftest test-map-let ()
+  (map-let (foo bar baz) '((foo . 1) (bar . 2))
+    (assert (= foo 1))
+    (assert (= bar 2))
+    (assert (null baz)))
+  (map-let ((foo . a)
+            (bar . b)
+            (baz . c)) '((foo . 1) (bar . 2))
+    (assert (= a 1))
+    (assert (= b 2))
+    (assert (null c))))
+
+(provide 'map-tests)
+;;; map-tests.el ends here