[TYPES] Types of expressions in dynamic languages: "un-typed" or "uni-typed"?
smcdirm at microsoft.com
Wed Jan 8 05:09:19 EST 2014
It is difficult to sort any type system into a simple easily named bucket.
I reserve "untyped" for languages where you don't even get a decent message-not-understood run-time error (e.g. a memory corruption in C on doing something bad to a void*). Untyped is much weaker than a safe dynamic language that crashes more elegantly (and more easily debugged) when a type error occurs.
I agree that the concept of uni-typing isn't very useful; it doesn't tell us very much about the real typing properties of the language.
From: Types-list [mailto:types-list-bounces at lists.seas.upenn.edu] On Behalf Of Siraaj Khandkar
Sent: Wednesday, January 8, 2014 11:12 AM
To: types-list at lists.seas.upenn.edu
Subject: [TYPES] Types of expressions in dynamic languages: "un-typed" or "uni-typed"?
[ The Types Forum, http://lists.seas.upenn.edu/mailman/listinfo/types-list ]
We're having a discussion with a friend regarding the most accurate way to describe the typing situation in Python.
His view is that Python data are typed and variables un-typed, moreover, he proposes that the terms "un-typed" and "uni-typed" are practically equivalent.
At first it seemed somewhat reasonable to me, but the more I thought about it, the more my mind rejected both, the equivalence and the phrasing.
The idea of uni-typing is that there's a set of types that the runtime supports and expressions can be composed of any members of that set, thus forming a single type, which is that set. This idea seems to describe the situation in a useful (for analysis) and an enlightening way, while the term "un-typed" does not seem to say anything useful.
I'm also feeling uneasy about the phrasing: un-typed _variables_. That is, data and _expressions_ have types, but individual variables are just not something you can make a claim about outside of a context of an expression.
We'd appreciate very much if the enlightened folks of this list would provide some input on this.
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