evalNone.lean:1:6-1:10: error: don't know how to synthesize implicit argument `α`
  @none ?m
context:
⊢ Type ?u
evalNone.lean:3:6-3:14: error: don't know how to synthesize implicit argument `α`
  @List.head? ?m []
context:
⊢ Type ?u
evalNone.lean:3:6-3:8: error: don't know how to synthesize implicit argument `α`
  @List.nil ?m
context:
⊢ Type ?u