🚀 go-pugleaf

In article <BEVAN.92Apr9151907@panda.cs.man.ac.uk>, bevan@cs.man.ac.uk (Stephen J Bevan) writes:
|> [...]
|>    The word `type' has no meaning at all if all attributes are
|>    dynamically alterable.
|> 
|> I would have thought it did, the "type" is just the "type" at the
|> particular time you look at it.  I'd consider this "dynamic typing".

Ok.  But what is your criterion for determining which properties of 
an object are `type' and which properties are just `value'.  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.

At both ends of the language spectrum, the definition I gave for type
is meaningless.  In pure functional languages, _no_ property of an
object is dynamic in a given scope.  So, by my definition, all
attributes (including those normally called `value') are type
attributes.  In a typeless language (say, SmallTalk for variation
in the discussion) all the attributes associated with a name can
be assigned.  So, by my definition, none of these attributes are
type attributes.  In between these extremes are the only languages
in which the word `type' is meaningfully distinguished from `value'.
In my opinion.

(The above is not quite true of SmallTalk.  The distinction between
a global variable and a temporary or local one is determined by the
syntax of the identifier - with globals starting with an initial 
capital letter and others beginning with a lower case letter.  So
this property qualifies as a type attribute by my definition.)

J. Giles