cofunIntoStreamPlusStream.err

MiniAgda by Andreas Abel and Karl Mehltretter
--- opening "cofunIntoStreamPlusStream.ma" ---
--- scope checking ---
--- type checking ---
type  Unit : Set
term  Unit.unit : < Unit.unit : Unit >
type  Bool : Set
term  Bool.true : < Bool.true : Bool >
term  Bool.false : < Bool.false : Bool >
type  Twice : ++(A : Set) -> Set
term  Twice.inl : .[A : Set] -> ^(y0 : A) -> < Twice.inl y0 : Twice A >
term  Twice.inr : .[A : Set] -> ^(y0 : A) -> < Twice.inr y0 : Twice A >
term  fmap : .[A : Set] -> .[B : Set] -> (A -> B) -> Twice A -> Twice B
{ fmap [A] [B] f (Twice.inl a) = Twice.inl (f a)
; fmap [A] [B] f (Twice.inr a) = Twice.inr (f a)
}
type  BStr : - Size -> Set
term  BStr.cons : .[i : Size] -> ^(head : Bool) -> ^(tail : BStr i) -> < BStr.cons i head tail : BStr $i >
term  head : .[i : Size] -> (cons : BStr $i) -> Bool
{ head [i] (BStr.cons [.i] #head #tail) = #head
}
term  tail : .[i : Size] -> (cons : BStr $i) -> BStr i
{ tail [i] (BStr.cons [.i] #head #tail) = #tail
}
term  idAndLast : .[i : Size] -> BStr i -> Twice (BStr i)
error during typechecking:
idAndLast
/// clause 1
/// pattern $i
/// checkPattern $i : matching on size, checking that target .[i : Size] -> BStr i -> Twice (BStr i) ends in correct coinductive sized type
/// new i <= #
/// endsInSizedCo: BStr i -> Twice (BStr i)
/// new  : (BStr v0)
/// endsInSizedCo: Twice (BStr i)
/// endsInSizedCo: target Twice (BStr i) of corecursive function is neither a CoSet or codata of size i nor a tuple type