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From: "Nasser M. Abbasi" <nma@12000.org>
Newsgroups: comp.lang.ada
Subject: Build language with weak typing,
 then add scaffolding later to strengthen
 it?
Date: Thu, 21 May 2015 14:11:44 -0500
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Date: 2015-05-21T14:11:44-05:00
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There seems to be strange thing going on with computer language design,
that I think folks here more than anywhere else would understand due
to Ada strong software engineering foundation.

I noticed languages start with weak or no typing at all. Then
later in the language life, lint like processing and type
hints are added to "strengthen" the language by making
it more strongly typed and catch more errors. Programmers
get excited each time a new scaffolding tool is added
since it now makes their language "better".

But why not then design the language with strong typing in
first place? Would not this be easier?

It is like constructing a building on weak foundation,
then add scaffolding on it later on to make it stronger.

Here is an example: Python now is adding what is called
"type hints" and everyone is excited about it since
it is supposed to make python more robust:

https://www.python.org/dev/peps/pep-0484/

"While these annotations are available at runtime
through the usual __annotations__ attribute, no type checking
happens at runtime . Instead, the proposal assumes the
existence of a separate off-line type checker which users
can run over their source code voluntarily. Essentially,
such a type checker acts as a very powerful linter. "

And we all know that C has lint also, to help catch
errors in code since C is weakly typed as well.

Fortran adds many compiler switches to help catch compile
time errors which otherwise would escape. I now use

gfortran -fcheck=all -Wall -Wconversion -Wextra -Wconversion-extra -pedantic

To make sure I checked everything, and I am still not sure it
did. (many times I download Fortran source code from the net
for fun and compile it using the above, and I see many
warnings generated, many due to mixed typing mess. It is scary).

In Ada, none of this is needed, as the language itself is designed
from the foundation to catch all these errors due to its
strong typing.

So, why do language designers design computer languages with weak
typing, and then spend so much effort later on to fixing the
weak typing? Is it because it is easier to design a language with
weak typing than strong one?

--Nasser