type (!'a, !'c, !'ty, 'nullable) t = 'a
constraint
'a =
< graphql_arg : ( unit -> 'ty Schema.Arg.arg_typ ) Core_kernel.ref
; map : ( 'ty -> 'c ) Core_kernel.ref
; nullable_graphql_arg :
( unit -> 'nullable Schema.Arg.arg_typ ) Core_kernel.ref
; skip : bool Core_kernel.ref.. >