applyMutation :: Expression -> Context -> Context
applyMutation (Mutation Define (Symdef sym) value) context =
  bindPair Dyn context (sym, value)
applyMutation :: Expression -> Context -> Context
applyMutation (Mutation Define (Symdef sym) value) context =
  bindPair Dyn context (sym, value)
applyMutation (Mutation Define (Symdef sym) value) context =
  bindPair Dyn context (sym, value)