On Thu, 14 Jul 2005, Andrew Pimlott wrote:
I would like to bristle mildly against the style of using Vector.T to represent the vector type. The reasons are 1) it is cryptic to those not used to the convention;
What does this tell about the quality of the concept?
2) enshrining one-type-per-module in the naming convention is not IMO justified, and may prove limiting;
Other languages like Modula-3 and Oberon do it with great success. The limit in Haskell is that most compilers don't conform to the Haskell 98 report which allows mutually recursive modules. But I think the compilers should allow them instead of forcing users to put many type and class definitions into one module.
3) it doesn't work out well when you import a module that reexports Vector.
Reexporting is only necessary for unqualified naming style. Vector.T is just the consequence of removing type-related prefixes from all identifiers. If you stick to qualified naming you only need to import the module once. Otherwise you must import a module twice. import LinearAlgebra.Vector (Vector) import qualified LinearAlgebra.Vector as V With this style importing as Vector is even not possible and you have to manage two abbreviations of the module. Setting up one module per data type (there are certainly auxiliary types which don't need it) allows a very clean and consistent naming style: DataType.T for the main type DataType.from* for conversions to that type DataType.to* for conversions into other types DataType.* for other functions related to that type It also answers the question whether the module name should be in singular or in plural form.
I would say leave it Vector.Vector. Then the user may import the module unqualified, or qualified with an abbreviation like V, define his own synonym ("type Vector = Vector.Vector"),
What about import qualified LinearAlgebra.Vector as V type Vector = V.T ?
1) If I define
foo :: Vector.T a -> Matrix.T a
Haddock (version 0.6) shows just this:
foo :: T a -> T a
I think this is evidence that trying to treat the "primary type" as a special case in naming creates more annoyances than it eliminates.
Haddock could adapt the type synonymes that are used in the signatures, or if it shall make the type names more uniform it could look how the modules are imported. That is, if a module is imported qualified the type should be shown qualified with the proposed abbreviation. Following the hyperlink of the type the user can check what the abbreviated module name means.