Create data constructor for partially applied type in Haskell -

is possible create data constructor partially applied type in haskell?

ghci session:

prelude> data vector b = vector {x::a, y::b} prelude> :t vector vector :: -> b -> vector b prelude> type t1 = vector int prelude> :t t1 <interactive>:1:1: not in scope: data constructor `t1' prelude> let x = vector prelude> let y = t1 <interactive>:46:9: not in scope: data constructor `t1' 

i want create data constructor type t1 - possible? or have use newtypes, because not possible manually define such function?

i'm little confused goal is, let's go through bit bit, , maybe i'll hit right point:

:t tells type of variable; makes no sense when applied type, since return passed. notice errors here tell :t expects kind of data value parameter:

prelude> :t maybe  <interactive>:1:1: not in scope: data constructor `maybe' prelude> :t (maybe integer)  <interactive>:1:2: not in scope: data constructor `maybe'  <interactive>:1:8: not in scope: data constructor `integer' 

you can create partial type:

prelude> type t = maybe prelude> 5 :: t integer 5  type t = maybe -- alternately, explicit type parameters prelude> 'a' :: t char 'a' 

you can't create data constructor partial type, since don't represent data. values maybe or vector have without being parameterized on type? might inclined think maybe have value nothing, nothing typed as:

prelude> :t nothing nothing :: maybe 

the key being nothing can any maybe a, still needs a know it's nothing. (it's sort of if told "fetch me glass of" instead of "fetch me glass of anything" - can't validly comply until i've @ least finished thought).

you can create partially applied functions return complete type once they're applied:

prelude> let f = :: -> t prelude> f 5 5 prelude> :t f 'a' f 'a' :: t char