A data type which contains itself. The commonest example is the list type, in Haskell: data List a = Nil | Cons a (List a) which says a list of a' s is either an empty list or a {cons cell} containing an ' a' (the "head" of the list) and another list (the "tail"). Recursion is not allowed in Miranda or Haskell {synonym type}s, so the following {Haskell} types are illegal: type Bad = (Int, Bad) type Evil = Bool -> Evil whereas the seeminly equivalent algebraic data types are acceptable: data Good = Pair Int Good data Fine = Fun (Bool->Fine)

In addition suitable contents:
[ = ] [ accept ] [ ad ] [ ai ] [ al ] [ algebra ] [ algebraic ] [ algebraic data type ] [ am ] [ an ] [ ar ] [ arc ] [ as ] [ at ] [ B ] [ b ] [ br ] [ C ] [ cc ] [ cell ] [ ch ] [ co ] [ com ] [ con ] [ cons ] [ cu ] [ data ] [ data type ] [ du ] [ E ] [ ec ] [ ed ] [ ee ] [ eg ] [ er ] [ es ] [ fi ] [ file ] [ fo ] [ Fun ] [ G ] [ ga ] [ ge ] [ Go ] [ h ] [ hr ] [ id ] [ il ] [ in ] [ io ] [ ir ] [ is ] [ it ] [ ke ] [ legal ] [ Lex ] [ li ] [ list ] [ ly ] [ M ] [ Miranda ] [ mm ] [ mo ] [ mod ] [ module ] [ mp ] [ N ] [ na ] [ ne ] [ ng ] [ ni ] [ nl ] [ no ] [ ns ] [ nym ] [ om ] [ pe ] [ ph ] [ pl ] [ pt ] [ query ] [ rc ] [ re ] [ sa ] [ say ] [ se ] [ si ] [ sk ] [ so ] [ st ] [ sy ] [ T ] [ table ] [ th ] [ type ] [ va ] [ vi ] [ win ]