Popularity
7.1
Stable
Activity
0.0
Declining
27
3
1

Monthly Downloads: 50
Programming language: Haskell
License: MIT License
Tags: Data     Types     Type System    
Latest version: v0.1.4

compound-types alternatives and similar packages

Based on the "Data" category.
Alternatively, view compound-types alternatives based on common mentions on social networks and blogs.

Do you think we are missing an alternative of compound-types or a related project?

Add another 'Data' Package

README

Intro

This library provides first-class multi-arity product- and sum-types and neat type-level utilities for their composition. The solution is quite simple and doesn’t require the advanced proficiency in the language to be applied in practice.

Here's an example of what you can do with it:

-- |
-- This function exhibits the benefit of the first-class sum-type
-- being usable as a function parameter.
-- 
-- It also shows, how we can pattern-match it.
intCharBoolSumToString :: (Int + Char + Bool) -> String
intCharBoolSumToString =
  \case
    Sum3_1 int -> "Int: " <> show int
    Sum3_2 char -> "Char: " <> show char
    Sum3_3 bool -> "Bool: " <> show bool

-- |
-- Following is an example of a more complicated composition,
-- which is the same as the following type:
-- 
-- > Sum3 Int (Product2 Char (Sum2 Bool String)) Char
-- 
-- Just as in the math, the product operator exhibits a higher priority.
type SumAndProductMixture =
  Int + Char * (Bool + String) + Char

-- |
-- Where there is a multiplication and addition,
-- there naturally must be a division and subtraction!
-- 
-- Following is an example of how we can extract parts of a composite type.
-- Here the type becomes the same as the following:
-- 
-- > Bool + String
type BoolOrString =
  (SumAndProductMixture - Int - Char) / Char

Compatibility

The library supports GHC starting from version 8.6.1 and requires you to enable the NoStarIsType extension.

Links