[Python-3000] Draft pre-PEP: function annotations (original) (raw)

Paul Prescod paul at prescod.net
Tue Aug 15 15:56:18 CEST 2006

On 8/14/06, Phillip J. Eby <pje at telecommunity.com> wrote:

At 1:51 PM 8/14/2006 -0700, "Paul Prescod" <paul at prescod.net> wrote: >On 8/14/06, Jim Jewett <jimjjewett at gmail.com> wrote: > > The definition of a type as an annotation should probably be either > > defined or explicitly undefined. Earlier discussions talked about > > things like > > > > def f (a:int, b:(float | Decimal), c:[int, str, X]) ->str) > > >I think that's a separate (large!) PEP. This PEP should disallow frameworks >from inventing their own meaning for this syntax (requiring them to at least >wrap). Then Guido and crew can dig into this issue on their own schedule. I see we haven't made nearly as much progress on the concept of "no predefined semantics" as I thought we had. :(

i.e., -1 on constraining what types mean.

I don't understand what you're saying.

  1. Do you (still?) agree that the meaning of the list type should be defined as a semantically neutral container for other annotations?

  2. Do you (still?) agree that the meanings of ALL built-in types at the top-level should be reserved for the Python language designers and should not be randomly used by framework developers. In other words: the function type declaration syntax above should not be used by one third party type checker while another third-party type checker uses the same structure to mean something totally different. Note that I don't mind if they have conflicting semantics for the same expression as long as the end-user is forced to declare which semantic model they are using:

tc = typechecker.typecheck tl = typelinter.check_types

def f (a:tc(int), b:tc(float | Decimal), c:tc([int, str, X])) -> tc(str)

def g (a:tl(int), b:tl(float | Decimal), c:tl([int, str, X])) -> tl(str)

  1. Do you agree that 1. and 2. together promotes the experimentation and variety that we need?

def f (a: [tc(int),tl("Integer")] b: [tc(float | Decimal), tl(Or("float", "Decimal")] c: [tc([int, str, X]), tl(listOf("Integer", "string", "X"))] ) -> [tc(str), tl(str)]

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