# typerep-map ![electricity](https://user-images.githubusercontent.com/8126674/44323413-788dd700-a484-11e8-842e-f224cfaa4206.png) [![Hackage](https://img.shields.io/hackage/v/typerep-map.svg)](https://hackage.haskell.org/package/typerep-map) [![Build status](https://secure.travis-ci.org/kowainik/typerep-map.svg)](https://travis-ci.org/kowainik/typerep-map) [![MIT license](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/vrom911/typerep-map/blob/master/LICENSE) `typerep-map` introduces `TMap` and `TypeRepMap` — data structures like [`Map`](http://hackage.haskell.org/package/containers-0.6.0.1/docs/Data-Map-Lazy.html#t:Map), but where types serve as keys, and values have the types specified in the corresponding key spots. For the more details on the implementation see [this blog post](https://kowainik.github.io/posts/2018-07-11-typerep-map-step-by-step.html). ## Usage example ```haskell ghci> import Data.TMap ghci> tm = insert True $ one (42 :: Int) ghci> size tm 2 ghci> res = lookup tm ghci> res :: Maybe Int Just 42 ghci> res :: Maybe Bool Just True ghci> res :: Maybe String Nothing ghci> lookup (insert "hello" tm) :: Maybe String Just "hello" ghci> member @Int tm True ghci> tm' = delete @Int tm ghci> member @Int tm' False ``` ## Benchmarks Tables below contain comparision with `DMap TypeRep` of ten `lookup` operations on structure with size `10^4`: | | ghc-8.2.2 | ghc-8.4.3 | |----------------|-----------|-----------| | `DMap TypeRep` | 517.5 ns | 779.9 ns | | `typerep-map` | 205.3 ns | 187.2 ns | ghc-8.2.2 | ghc-8.4.3 :---------:|:-----------: ![DMap 8.2.2](https://user-images.githubusercontent.com/4276606/42495129-c700f21e-8454-11e8-98b4-ba080259c712.png) | ![DMap 8.4.3](https://user-images.githubusercontent.com/4276606/42495168-ebb1d13c-8454-11e8-9d17-f6da29d2169a.png) ![TMap 8.2.2](https://user-images.githubusercontent.com/4276606/42494935-3a352d96-8454-11e8-985e-ebc77cc51ca0.png) | ![TMap 8.4.3](https://user-images.githubusercontent.com/4276606/42495147-d884bdf4-8454-11e8-887f-9815fd2b8d68.png)