map Size in Haskell

In Haskell, the Data.HashMap.Strict module provides a size function to get the number of key-value pairs in a hash map.

Here's an example using the Data.HashMap.Strict module:

import qualified Data.HashMap.Strict as Map
myMap = Map.fromList [("a", 1), ("b", 2), ("c", 3)]

sizeOfMyMap = Map.size myMap
main = do

  putStrLn "Size of myMap:"

  print sizeOfMyMap

The fromList function creates a new hash map from a list of key-value pairs, and size returns the number of key-value pairs in the hash map. In this example, sizeOfMyMap should be 3.

Here's another example using the Data.HashTable.ST.Basic module:

import qualified Data.HashTable.ST.Basic as HashTable
main = do

  ht <- HashTable.new

  HashTable.insert ht "a" 1

  HashTable.insert ht "b" 2

  HashTable.insert ht "c" 3

  sizeOfHashTable <- HashTable.size ht

  putStrLn "Size of hash table:"

  print sizeOfHashTable

In this example, new creates a new hash table, insert adds key-value pairs to the hash table, and size returns the number of key-value pairs in the hash table. In this example, sizeOfHashTable should be 3.