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Define an unmodifiable empty map
; Clojure maps are immutable
(def m {})
(def m {})
const std::map<T1,T2> immutable_map_instance_of_type_t1_to_t2;
% Erlang data structures are immutable - updating a 'map' sees a modified copy created
Map = dict:new(),
map := [:].ro
// Most native fsharp data structures are immutable - updating a 'map' sees a modified copy created
let map = Map.empty
let map = Map.empty
empty = Collections.EMPTY_MAP
map = [:].asImmutable()
def empty = MapUtils.EMPTY_SORTED_MAP
def empty = ImmutableMap.of()
import qualified Data.Map as Map
output :: Map.Map k v
output = Map.empty
output :: Map.Map k v
output = Map.empty
Map empty = Collections.EMPTY_MAP;
SortedMap empty = MapUtils.EMPTY_SORTED_MAP;
(* OCaml maps are functional data structures (so are immutable) *)
module StringMap = Map.Make (String)
let m = StringMap.empty
module StringMap = Map.Make (String)
let m = StringMap.empty
# perl does not provide unmodifiable maps/hashes, but you could use "constant
# functions", if you really need them
# 2011-07-06 Not actually true, see Hash::Util::lock_hash;
sub MAP () { {} }
# functions", if you really need them
# 2011-07-06 Not actually true, see Hash::Util::lock_hash;
sub MAP () { {} }
use Hash::Util qw/lock_hash/;
# two lines
my %hash;
lock_hash(%hash);
# or in one line
lock_hash(my %locked_hash);
# two lines
my %hash;
lock_hash(%hash);
# or in one line
lock_hash(my %locked_hash);
/* It's not possible to define an array as a constant
* Instead we can use the serialize-function */
$fruits = array("apple", "banana", "orange");
define("FRUITS", serialize($fruits));
echo FRUITS; // a:3:{i:0;s:5:"apple";i:1;s:6:"banana";i:2;s:6:"orange";}
$my_fruits = unserialize(FRUITS); // and normal array again
* Instead we can use the serialize-function */
$fruits = array("apple", "banana", "orange");
define("FRUITS", serialize($fruits));
echo FRUITS; // a:3:{i:0;s:5:"apple";i:1;s:6:"banana";i:2;s:6:"orange";}
$my_fruits = unserialize(FRUITS); // and normal array again
import collections
EmptyDict = collections.namedtuple("EmptyDict", "")
e = EmptyDict()
EmptyDict = collections.namedtuple("EmptyDict", "")
e = EmptyDict()
map = {}.freeze
val map = immutable.Map.empty
val map = immutable.TreeMap.empty[String, Int]
val map = Map()
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