nicuveo

[alias]
	st = status
	ci = commit
	co = checkout
	br = branch
	ff = merge --ff-only
	fa = fetch --all
	rh = reset --hard
	cp = cherry-pick
	d = diff --color

nicuveo

{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE LambdaCase    #-}

import           Control.Applicative (liftA2)
import           Data.Char
import           Data.Foldable       (for_)
import           Data.Functor
import qualified Data.HashMap.Strict as M
import           Data.List           (intercalate)
import           Prelude             hiding (any)

nicuveo

{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE InstanceSigs        #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications    #-}
{-# LANGUAGE TypeFamilies        #-}

module Foo where

import           Control.Monad.Reader
import           Data.Kind            (Type)

nicuveo

{-# LANGUAGE CPP                 #-}
{-# LANGUAGE DataKinds           #-}
{-# LANGUAGE DeriveDataTypeable  #-}
{-# LANGUAGE FlexibleContexts    #-}
{-# LANGUAGE GADTs               #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE StandaloneDeriving  #-}
{-# LANGUAGE TypeApplications    #-}
{-# LANGUAGE TypeFamilies        #-}

nicuveo

all:
	ghc --version
	ghc -Wredundant-constraints -Werror -O0 Main.hs
	ghc -Wredundant-constraints -Werror -O2 Main.hs

nicuveo

{-# LANGUAGE AllowAmbiguousTypes  #-}
{-# LANGUAGE DataKinds            #-}
{-# LANGUAGE PolyKinds            #-}
{-# LANGUAGE TypeFamilies         #-}
{-# LANGUAGE TypeOperators        #-}
{-# LANGUAGE UndecidableInstances #-}

import           Data.Kind      (Type)
import           Data.Type.Bool

nicuveo

{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications    #-}

import           Data.Proxy
import           Data.Typeable

contains :: forall a b. (Typeable a, Typeable b) => Bool
contains = go typeB
  where typeA = typeRep (Proxy :: Proxy a)

nicuveo

{"type":"http-log","timestamp":"2020-03-31T00:05:40.203+0000","level":"error","detail":{"operation":{"user_vars":{"x-hasura-role":"admin"},"error":{"internal":{"statement":"DO $$ DECLARE  r RECORD;  BEGIN    FOR r IN (SELECT routine_name FROM information_schema.routines WHERE specific_schema = 'hdb_views' ORDER BY routine_name) LOOP      EXECUTE 'DROP FUNCTION hdb_views.' || quote_ident(r.routine_name) || '() CASCADE';    END LOOP;  END $$; ","prepared":false,"error":{"exec_status":"FatalError","hint":null,"message":"cannot execute DROP FUNCTION in a read-only transaction","status_code":"25006","description":null},"arguments":[]},"path":"$.args[0].args","error":"postgres query error","code":"unexpected"},"request_id":"51d1a76d-8688-4905-a913-f1be94bc8df5","response_size":566,"query":{"args":[{"args":{"cascade":false,"check_metadata_consistency":null,"sql":"SELECT\n  COALESCE(Json_agg(Row_to_json(info)), '[]' :: json) AS tables\nFROM (\n  SELECT\n    pgn.nspname as table_schema,\n    pgc.relname as table_name,

nicuveo

{-# LANGUAGE FlexibleContexts       #-}
{-# LANGUAGE FlexibleInstances      #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE UndecidableInstances   #-}


-- no data kinds, pure type level
-- let's start by defining booleans and numbers

data True

nicuveo

{-# LANGUAGE DataKinds         #-}
{-# LANGUAGE FlexibleContexts  #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TypeFamilies      #-}
{-# LANGUAGE TypeOperators     #-}


import           Data.Proxy
import           GHC.TypeLits