containers
Introduction¶
The containers
package provides implementations of various 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 containers Haddocks to check out the full API documentation!
Provided Data Structures¶
- Sets: ordered, non-duplicated elements
- Maps: ordered maps from keys to values (aka. dictionaries)
- Sequences: finite sequence of elements, an efficient alternative to list
Note
You’ll need containers >= 0.5.9
for a few of the examples. See
Version Requirements for info on how to check which version you have and
how to upgrade.
Looking for more resources?¶
If you’ve worked your way through the documentation here and you’re looking for more examples or tutorials you should check out:
Installing and using the containers
package¶
Version Requirements¶
For some of the examples you’ll need containers >= 0.5.9
which ships with
GHC >= 8.2
. You can check to see which version you have installed with:
ghc --version
> The Glorious Glasgow Haskell Compilation System, version 8.2.2
If you have an older version, don’t worry about it, the majority of the code
works with older versions of the package. If you want, you can get a recent
version by from haskell.org, or with
Stack using something like
stack --resolver lts-20.14 ghci
(see Stackage
for the latest long-term support (LTS) or nightly resolver version).
Importing modules¶
All of the modules in containers
should be imported qualified
since they
use names that conflict with the standard Prelude.
import qualified Data.Set as Set
import qualified Data.Map.Strict as Map
import qualified Data.Sequence as Seq