Purescript variadic function - function with variable number of arguments of variable type

printf.purs

module Main where

import Prelude (class Show, Unit, ($), show, (++), (<<<))
import Control.Monad.Eff (Eff)
import Control.Monad.Eff.Console (CONSOLE, log)
import Data.String (joinWith)
import Data.ExistsR

class PrintF t where
  printf' :: Array String -> t
 
instance sprintfOut::PrintF String where
  printf' acc = joinWith " " acc
instance printfArg::(Show a, PrintF r) => PrintF (a -> r) where
  printf' acc = \x -> printf' (acc ++ [show x])

printf::forall t. (PrintF t) => t
printf = printf' []

newtype Record = Record (ExistsR Object)
instance showRecord::Show Record where
  show (Record r) = showRecordImpl r
foreign import showRecordImpl::ExistsR Object -> String

mkR::forall r. {|r} -> Record
mkR = Record <<< mkExistsR

main :: forall e. Eff (console::CONSOLE|e) Unit
main = do
  log $ printf "Record print: " (mkR {first:"John", last:"Doe" }) " Int= " 10