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DO NOT SUBMIT: Some partial conversion to Tutorial module.
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{-# OPTIONS_GHC -fno-warn-unused-imports #-} | ||
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{-| | ||
The @unordered-containers@ package provides implementations of various | ||
hash-based immutable data structures. | ||
Some of the data structures provided by this package have a very large API | ||
surface (for better or worse). The docs here focus on the most common functions | ||
which should be more than enough to get you started. Once you know the basics, | ||
or if you're looking for a specific function, you can head over to the | ||
full API documentation! | ||
-} | ||
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module Tutorial ( | ||
-- * Provided Data Structures | ||
-- $provideddatastructures | ||
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-- * Related Packages | ||
-- $relatedpackages | ||
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-- * Looking for more resources? | ||
-- $moreresources | ||
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-- * Installing and using the @unordered-containers@ packages | ||
-- $installing | ||
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-- * HashSet and HashMap tutorial | ||
-- $tutorials | ||
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) where | ||
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{- $provideddatastructures | ||
* 'Data.HashSet' - unordered, non-duplicated elements | ||
* 'Data.HashMap' - unordered map from keys to values (aka. dictionaries) | ||
-} | ||
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{- $relatedpackages | ||
* <https://hackage.haskell.org/packages/containers containers> - ordered containers using trees instead of hashing. | ||
* <https://hackage.haskell.org/packages/hashable containers> - types that can be converted to a hash value. | ||
-} | ||
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{- $moreresources | ||
If you've worked your way through the documentation here and you're looking for | ||
more examples or tutorials you should check out: | ||
* <https://haskell-lang.org/library/containers haskell-lang.org's containers tutorial>, its focused on the ordered | ||
<https://hackage.haskell.org/packages/containers containers> library but provides some useful examples. | ||
* <http://learnyouahaskell.com/modules Learn You a Haskell "Modules" chapter> | ||
-} | ||
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{- $installing | ||
__Version Requirements__ | ||
All of the examples here should work for all recent versions of the package. | ||
__Importing modules__ | ||
All of the modules in @unordered-containers@@ should be imported @qualified@ | ||
since they use names that conflict with the standard Prelude. | ||
@ | ||
import qualified Data.HashSet as HashSet | ||
import qualified Data.HashMap.Strict as HashMap | ||
@ | ||
__In GHCi__ | ||
Start the GHCi | ||
<https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop REPL> with | ||
@ghci@, @cabal repl@, or @stack ghci@. Once the REPL is loaded, import the | ||
modules you want using the @import@ statements above and you're good to go! | ||
-} | ||
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{- $tutorials | ||
See "Tutorial.HashSet" and "Tutorial.HashMap". | ||
-} |
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{-# OPTIONS_GHC -fno-warn-unused-imports #-} | ||
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{-| | ||
Sets allow you to store *unique* elements, providing efficient insertion, | ||
lookups, and deletions. If you are storing sets of @Int@ s consider using | ||
'Data.IntSet' from the <https://hackage.haskell.org/packages/containers containers> package. You can find the | ||
introductory documentation for @containers@ at | ||
<https://haskell-containers.readthedocs.io>. | ||
@ | ||
data HashSet element = ... | ||
@ | ||
All of these implementations are *immutable* which means that any update | ||
functions do not modify the set that you passed in, they creates a new set. In | ||
order to keep the changes you need to assign it to a new variable. For example: | ||
@ | ||
let s1 = HashSet.fromList ["a", "b"] | ||
let s2 = HashSet.delete "a" s1 | ||
print s1 | ||
> fromList ["a","b"] | ||
print s2 | ||
> fromList ["b"] | ||
@ | ||
__IMPORTANT:__ @HashSet@ relies on the @element@ type having instances of the @Eq@ and | ||
@Hashable@ typeclasses for its internal representation. These are already | ||
defined for builtin types, and if you are using your own data type you can | ||
use the | ||
<https://en.wikibooks.org/wiki/Haskell/Classes_and_types#Deriving deriving> | ||
mechanism. | ||
-} | ||
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module Tutorial.HashSet ( | ||
-- * Short Example | ||
-- $shortexample | ||
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) where | ||
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{- $shortexample | ||
The following GHCi session shows some of the basic set functionality: | ||
@ | ||
import qualified Data.HashSet as HashSet | ||
let dataStructures = HashSet.fromList ["HashSet", "HashMap", "Graph"] | ||
-- Check if "HashMap" and "Trie" are in the set of data structures. | ||
HashSet.member "HashMap" dataStructures | ||
> True | ||
HashSet.member "Trie" dataStructures | ||
> False | ||
-- Add "Trie" to our original set of data structures. | ||
let moreDataStructures = HashSet.insert "Trie" dataStructures | ||
HashSet.member "Trie" moreDataStructures | ||
> True | ||
-- Remove "Graph" from our original set of data structures. | ||
let fewerDataStructures = HashSet.delete "Graph" dataStructures | ||
HashSet.toList fewerDataStructures | ||
> ["HashSet", "HashMap"] | ||
-- Create a new set and combine it with our original set. | ||
let orderedDataStructures = HashSet.fromList ["Set", "Map"] | ||
HashSet.union dataStructures orderedDataStructures | ||
> fromList ["Map", "HashSet", "Graph", "HashMap", "Set"] | ||
@ | ||
__TIP__: You can use the `OverloadedLists | ||
<https://ghc.haskell.org/trac/ghc/wiki/OverloadedLists>`_ extension so | ||
you don't need to write ``fromList [1, 2, 3]`` everywhere. Instead you | ||
can just write ``[1, 2, 3]`` and if the function is expecting a set it | ||
will be converted automatically! The code here will continue to use | ||
``fromList`` for clarity though. | ||
-} |
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