Deprecated

tables

In-memory storage with multiple keys using lenses and traversals http://github.com/ekmett/tables/

Latest on Hackage:0.4.1.1

This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow stackage.org to host generated Haddocks.

BSD3 licensed by Edward A. Kmett
Maintained by Edward A. Kmett

Tables

Build Status

This package provides simple in memory data tables with multiple indices.

Examples

So if we load examples/Foo.hs into ghci, we start with:

>>> test
fromList [ Foo {fooId = 1, fooBar = "One", fooBaz = 1.0}
         , Foo {fooId = 2, fooBar = "Two", fooBaz = 2.0}
         , Foo {fooId = 3, fooBar = "Three", fooBaz = 3.0}
         , Foo {fooId = 4, fooBar = "Four", fooBaz = 4.0}
         , Foo {fooId = 5, fooBar = "Five", fooBaz = 5.0} ]

We use uppercase constructor names to match on built-in keys

>>> test ^. with FooId (<) 3
fromList [ Foo {fooId = 1, fooBar = "One", fooBaz = 1.0}
         , Foo {fooId = 2, fooBar = "Two", fooBaz = 2.0} ]

Then we can use any lowercase field accessor (or any other function) to do a non-keyed lookup or filter

>>> test ^. with (length . fooBar) (<=) 3
fromList [ Foo {fooId = 1, fooBar = "One", fooBaz = 1.0}
         , Foo {fooId = 2, fooBar = "Two", fooBaz = 2.0} ]

You can delete by assigning to that filtered table:

>>> test & with (length . fooBar) (<=) 3 .~ empty
fromList [ Foo {fooId = 3, fooBar = "Three", fooBaz = 3.0}
         , Foo {fooId = 4, fooBar = "Four", fooBaz = 4.0}
         , Foo {fooId = 5, fooBar = "Five", fooBaz = 5.0} ]

You can edit the actual type of the fields if the table is configured to allow it:

>>> test & rows.fooBar_ %~ length
fromList [ Foo {fooId = 1, fooBar = 3, fooBaz = 1.0}
         , Foo {fooId = 2, fooBar = 3, fooBaz = 2.0}
         , Foo {fooId = 3, fooBar = 5, fooBaz = 3.0}
         , Foo {fooId = 4, fooBar = 4, fooBaz = 4.0}
         , Foo {fooId = 5, fooBar = 4, fooBaz = 5.0} ]

If you edit multiple fields, the edits all take place at the same time. so we can offset or swap a bunch of keys:

>>> test & with FooId (>=) 2.rows.fooId_ +~ 1
fromList [ Foo {fooId = 1, fooBar = "One", fooBaz = 1.0}
         , Foo {fooId = 3, fooBar = "Two", fooBaz = 2.0}
         , Foo {fooId = 4, fooBar = "Three", fooBaz = 3.0}
         , Foo {fooId = 5, fooBar = "Four", fooBaz = 4.0}
         , Foo {fooId = 6, fooBar = "Five", fooBaz = 5.0} ]

We can do grouping by arbitrary functions or fields similarly

>>> test ^@.. group (length.fooBar)
[ (3, fromList [ Foo {fooId = 1, fooBar = "One", fooBaz = 1.0}
               , Foo {fooId = 2, fooBar = "Two", fooBaz = 2.0} ])
, (4, fromList [ Foo {fooId = 4, fooBar = "Four", fooBaz = 4.0}
               , Foo {fooId = 5, fooBar = "Five", fooBaz = 5.0} ])
, (5, fromList [Foo {fooId = 3, fooBar = "Three", fooBaz = 3.0} ])
]

Contact Information

Contributions and bug reports are welcome!

Please feel free to contact me through github or on the #haskell or #haskell-lens IRC channels on irc.freenode.net.

-Edward Kmett

Changes

0.4.1.1

  • GHC 7.10 compatibility

0.4.1

0.4

0.3.1

  • Improved Setup.lhs to work with more versions of cabal.
  • Internal compatibility with changes in lens 3.10 to anon.

0.3

  • Instances for SafeCopy, Binary and Cereal
  • Added insert'

0.2

  • Generalized Autoincrement
  • Better type inference for key types
  • More aggressive inlining

0.1

  • Initial public release
  • Repository initialized
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