patch 7.4.1989
Problem:    filter() and map() only accept a string argument.
Solution:   Implement using a Funcref argument (Yasuhiro Matsumoto, Ken
            Takata)
diff --git a/src/testdir/test_alot.vim b/src/testdir/test_alot.vim
index 76134fb..e8546ef 100644
--- a/src/testdir/test_alot.vim
+++ b/src/testdir/test_alot.vim
@@ -12,6 +12,7 @@
 source test_feedkeys.vim
 source test_fnamemodify.vim
 source test_file_perm.vim
+source test_filter_map.vim
 source test_glob2regpat.vim
 source test_goto.vim
 source test_help_tagjump.vim
diff --git a/src/testdir/test_filter_map.vim b/src/testdir/test_filter_map.vim
new file mode 100644
index 0000000..6bb063c
--- /dev/null
+++ b/src/testdir/test_filter_map.vim
@@ -0,0 +1,77 @@
+" Test filter() and map()
+
+" list with expression string
+func Test_filter_map_list_expr_string()
+  " filter()
+  call assert_equal([2, 3, 4], filter([1, 2, 3, 4], 'v:val > 1'))
+  call assert_equal([3, 4], filter([1, 2, 3, 4], 'v:key > 1'))
+
+  " map()
+  call assert_equal([2, 4, 6, 8], map([1, 2, 3, 4], 'v:val * 2'))
+  call assert_equal([0, 2, 4, 6], map([1, 2, 3, 4], 'v:key * 2'))
+endfunc
+
+" dict with expression string
+func Test_filter_map_dict_expr_string()
+  let dict = {"foo": 1, "bar": 2, "baz": 3}
+
+  " filter()
+  call assert_equal({"bar": 2, "baz": 3}, filter(copy(dict), 'v:val > 1'))
+  call assert_equal({"foo": 1, "baz": 3}, filter(copy(dict), 'v:key > "bar"'))
+
+  " map()
+  call assert_equal({"foo": 2, "bar": 4, "baz": 6}, map(copy(dict), 'v:val * 2'))
+  call assert_equal({"foo": "f", "bar": "b", "baz": "b"}, map(copy(dict), 'v:key[0]'))
+endfunc
+
+" list with funcref
+func Test_filter_map_list_expr_funcref()
+  " filter()
+  func! s:filter1(index, val) abort
+    return a:val > 1
+  endfunc
+  call assert_equal([2, 3, 4], filter([1, 2, 3, 4], function('s:filter1')))
+
+  func! s:filter2(index, val) abort
+    return a:index > 1
+  endfunc
+  call assert_equal([3, 4], filter([1, 2, 3, 4], function('s:filter2')))
+
+  " map()
+  func! s:filter3(index, val) abort
+    return a:val * 2
+  endfunc
+  call assert_equal([2, 4, 6, 8], map([1, 2, 3, 4], function('s:filter3')))
+
+  func! s:filter4(index, val) abort
+    return a:index * 2
+  endfunc
+  call assert_equal([0, 2, 4, 6], map([1, 2, 3, 4], function('s:filter4')))
+endfunc
+
+" dict with funcref
+func Test_filter_map_dict_expr_funcref()
+  let dict = {"foo": 1, "bar": 2, "baz": 3}
+
+  " filter()
+  func! s:filter1(key, val) abort
+    return a:val > 1
+  endfunc
+  call assert_equal({"bar": 2, "baz": 3}, filter(copy(dict), function('s:filter1')))
+
+  func! s:filter2(key, val) abort
+    return a:key > "bar"
+  endfunc
+  call assert_equal({"foo": 1, "baz": 3}, filter(copy(dict), function('s:filter2')))
+
+  " map()
+  func! s:filter3(key, val) abort
+    return a:val * 2
+  endfunc
+  call assert_equal({"foo": 2, "bar": 4, "baz": 6}, map(copy(dict), function('s:filter3')))
+
+  func! s:filter4(key, val) abort
+    return a:key[0]
+  endfunc
+  call assert_equal({"foo": "f", "bar": "b", "baz": "b"}, map(copy(dict), function('s:filter4')))
+endfunc
diff --git a/src/testdir/test_partial.vim b/src/testdir/test_partial.vim
index 6012507..b43f349 100644
--- a/src/testdir/test_partial.vim
+++ b/src/testdir/test_partial.vim
@@ -14,6 +14,14 @@
   return a:one < a:two ? 1 : -1
 endfunc
 
+func MyMap(sub, index, val)
+  return a:val - a:sub
+endfunc
+
+func MyFilter(threshold, index, val)
+  return a:val > a:threshold
+endfunc
+
 func Test_partial_args()
   let Cb = function('MyFunc', ["foo", "bar"])
 
@@ -36,6 +44,16 @@
   call assert_equal([1, 2, 3], sort([3, 1, 2], Sort))
   let Sort = function('MySort', [0])
   call assert_equal([3, 2, 1], sort([3, 1, 2], Sort))
+
+  let Map = function('MyMap', [2])
+  call assert_equal([-1, 0, 1], map([1, 2, 3], Map))
+  let Map = function('MyMap', [3])
+  call assert_equal([-2, -1, 0], map([1, 2, 3], Map))
+
+  let Filter = function('MyFilter', [1])
+  call assert_equal([2, 3], filter([1, 2, 3], Filter))
+  let Filter = function('MyFilter', [2])
+  call assert_equal([3], filter([1, 2, 3], Filter))
 endfunc
 
 func MyDictFunc(arg1, arg2) dict
@@ -60,6 +78,9 @@
   call assert_equal("hello/xxx/yyy", Cb("xxx", "yyy"))
   call assert_fails('Cb("fff")', 'E492:')
 
+  let Cb = function('MyDictFunc', dict)
+  call assert_equal({"foo": "hello/foo/1", "bar": "hello/bar/2"}, map({"foo": 1, "bar": 2}, Cb))
+
   let dict = {"tr": function('tr', ['hello', 'h', 'H'])}
   call assert_equal("Hello", dict.tr())
 endfunc