labels

Anonymous records via named tuples https://github.com/chrisdone/labels#readme

LTS Haskell 11.5:	0.3.3
Stackage Nightly 2018-04-21:	0.3.3
Latest on Hackage:	0.3.3

See all snapshots labels appears in

BSD3 licensed by Chris Done

Maintained by chrisdone@gmail.com

Module documentation for 0.3.3

Labels
- Labels.Internal

labels

Declare and access tuple fields with labels

This package is experimental, exploring the design space opened up by the implemented and to-be-implemented work on extensible records in GHC.

Note: You need GHC 8.0.1.

Basic examples

The haddock docs are here.

Enable these extensions:

In GHCi: :set -XOverloadedLabels -XTypeOperators -XDataKinds -XFlexibleContexts
In a module: {-# LANGUAGE OverloadedLabels, TypeOperators, DataKinds, FlexibleContexts #-}

Let's use GHCi:

> import Labels
> :set -XOverloadedLabels -XTypeOperators -XDataKinds -XFlexibleContexts

Construct a record	> (#foo := "hi", #bar := 123) (#foo := "hi",#bar := 123)
Get fields of a record	> get #bar (#foo := "hi", #bar := 123) 123
Set fields of a record	> set #bar 66 (#foo := "hi", #bar := 123) (#foo := "hi",#bar := 66)
Modify fields of a record	> modify #mu (*0.1) (#bar := "hi", #mu := 123) (#bar := "hi",#mu := 12.3)
Add fields to a record	> cons (#mu := [1,2,3]) (#foo := "hi", #bar := 123) (#mu := [1,2,3],#foo := "hi",#bar := 123)
Abstraction	> let double field record = set field (get field record * 2) record > double #mu (#bar := "hi", #mu := 123) (#bar := "hi",#mu := 246)

Changes

0.3.1:
* Export Labels class.

0.3.1:
* Add Subset class.

0.3.0:
* Put labels in its own class.
* Change type of labels to take a Proxy.

0.2.0:
* Add "reflect" and "labels" functions.
* Drop support for GHC <8.

0.1.2:
* Add docs for "project" function.

0.1.1:
* Add "project" function.

0.1.0:
* Drop the convenience accessor #foo. Must use get #foo

0.0.0:
* First version

Depends on 2 packages:

base, template-haskell

Used by 1 package:

acme-everything