🚀 go-pugleaf

In article <BEVAN.92Apr10180934@panda.cs.man.ac.uk> bevan@cs.man.ac.uk (Stephen J Bevan) writes:
|In article <1992Apr10.095151.28116@newshost.lanl.gov> jlg@cochiti.lanl.gov (Jim Giles) writes:
|   I specified an explicit criterion for deciding what constitutes
|   type: those properties which are permanently associated with a name
|   (or function, expression, etc.) regardless of run-time variations.
|
|And I objected, because I think this is one particular type of `type'
|namely the `static type' of the object.  Whilst it is true that in a
|certain class of languages there is no difference between the `static'
|and `dynamic' type of an object, I don't think you can generalise to
|saying that this means `type' = `static type' and the `dynamic type'
|somehow isn't a `type'.

Wait, wait! Are we talking about LEXICAL occurrences of names or about
INSTANCES? These are profoundly different. Consider the parametric
polymorphic identity function (nonce-notation, . is
lambda-abstraction):

	f: TYPE => (T . T -> T) = T . t . t

Is "t" statically typed? Its type is "T" which is itself an argument
to f.... Statically bound but not lexically bound, I would have said,
but perhaps that isn't the clearest way of expressing it.

|   In a typeless language (say, SmallTalk for variation in the
|   discussion)
|
|Smalltalk is not "typeless" as far as I'm concerned, it has strong,
|dynamic (or latent) types.

I would have said it was unityped: it has *one* type for objects,
which is (formally, internally) a dependent product:

	TYPE =, (T . T)

(Pardon notation!). But strongly typed, certainly.
----------------------------------------------------------------------
stephen p spackman         Center for Information and Language Studies
stephen@estragon.uchicago.edu                    University of Chicago
----------------------------------------------------------------------