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From: Paul Rubin <no.email@nospam.invalid>
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Subject: Re: In precision typing we trust
Date: Tue, 26 Aug 2025 17:00:58 -0700
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Kevin Chadwick <kc-usenet@chadwicks.me.uk> writes:
> Wouldn't that make Python slow and unreliable?

It's slow but that's due to the rather simple implementation.  SBCL
Common Lisp is reasonably fast.  Python is reasonably reliable in the
sense that programs with errors will probably crash instead of going off
into the weeds.  The saying is that correct code is great, code that
crashes could use improvement, but incorrect code that keeps running and
delivering wrong results is a disaster.

Joe Armstrong (inventor of Erlang) also liked to say that there is no
such thing as a reliable non-distributed system, since the power cord is
a single point of failure By that standard, Ada isn't so reliable
either.

[Dmitry A. Kazakov writes:]

> The error occurred inside the body of F. F itself was successfully
> called, because it is untyped. Just as I said.

F didn't encounter a type error until it tried to do arithmetic on its
argument.  If it instead called its argument based on some decision,
that wouldn't have been a type error.  You don't get to decide whether
that counts as a type system or not.  It's just a coarser version of Ada
doing runtime checks on array subscripts and integer overflow, instead
of statically verifying that they are in range (a proof system like Agda
would consider those to also be type errors).

Same article I posted before, "What to know before debating type
systems":

https://blogs.perl.org/users/ovid/2010/08/what-to-know-before-debating-type-systems.html