content: 
  module Language.BackEnd.Evaluator.Types where
  
  -- ─── IMPORTS ────────────────────────────────────────────────────────────────────
  
  import Language.FrontEnd.AST
  import Model
  
  -- ─── MAIN ───────────────────────────────────────────────────────────────────────
  
  type EvalResult = Either String Double
  
  type EvalFunction = AST -> Model -> EvalResult
  
  type LeafEvalSignature = EvalFunction
  
  type StemEvalSignature = ( LeafEvalSignature ) -> LeafEvalSignature
  
  type MasterEvalResult = Either String MasterEvalResultRight
  
  data MasterEvalResultRight =
      MasterEvalResultRight [ Double ] Model
  
  -- ────────────────────────────────────────────────────────────────────────────────
  