yesodweb/persistent

derivePersistField phantom type support

Aperta

#1137 aperta il 23 ott 2020

 (8 commenti) (0 reazioni) (1 assegnatario)Haskell (302 fork)auto 404
Feature Requestgood first issue

Metriche repository

Star
 (484 stelle)
Metriche merge PR
 (Metriche PR in attesa)

Descrizione

Phantom types are very useful for tagging things on type level, but at the moment this code will not compile

-- @Employment.hs
{-# LANGUAGE TemplateHaskell #-}
module Employment where

import Database.Persist.TH
import Prelude

data Employment a = Employed | Unemployed | Retired
    deriving (Show, Read, Eq)
derivePersistField "Employment a"

Guida contributor