Joachim Durchholz wrote: > Andreas Rossberg schrieb: > >> Luca Cardelli has given the most convincing one in his seminal >> tutorial "Type Systems", where he identifies "typed" and "safe" as two >> orthogonal dimensions and gives the following matrix: >> >> | typed | untyped >> -------+-------+---------- >> safe | ML | Lisp >> unsafe | C | Assembler >> >> Now, jargon "dynamically typed" is simply untyped safe, while "weakly >> typed" is typed unsafe. > > Here's a matrix how most people that I know would fill in with terminology: > > | Statically | Not | > | typed | statically | > | | typed | > ---------+--------------+-------------+ > typesafe | "strongly | Dynamically | > | typed" | typed | > | (ML, Pascal) | (Lisp) |
Pascal, in most of its implementations, isn't [memory] safe; it's in the same box as C. > ---------+--------------+-------------+ > not | (no common | "untyped" | > typesafe | terminology) | | > | (C) | (Assembly) | > ---------+--------------+-------------+ I have to say that I prefer the labels used by Cardelli. > (Terms in quotes are challenged on a regular basis, or rarely if ever > applied.) > > With the above terminology, it becomes clear that the opposite if > "(statically) typed" isn't "statically untyped", but "not statically > typed". "Statically typed" and "dynamically typed" aren't even > opposites, they just don't overlap. > > Another observation: type safeness is more of a spectrum than a clearcut > distinction. Even ML and Pascal have ways to circumvent the type system, Standard ML doesn't (with just the standard basis; no external libraries, and assuming that file I/O cannot be used to corrupt the language implementation). > and even C is typesafe unless you use unsafe constructs. > IOW from a type-theoretic point of view, there is no real difference > between their typesafe and not typesafe languages in the "statically > typed" column; the difference is in the amount of unsafe construct usage > in practial programs. It is quite possible to design languages that have absolutely no unsafe constructs, and are still useful. -- David Hopwood <[EMAIL PROTECTED]> -- http://mail.python.org/mailman/listinfo/python-list
