[Pharo-dev] Smalltalk = strongly typed

btc at openinworld.com btc at openinworld.com
Fri Aug 2 00:03:03 EDT 2013


greetings all,

I'm in the final weeks of writing up my Masters dissertation and seeking 
some scholarly references to Smalltalk being "Strongly Typed."

I my review of Smalltalk I was surprised to find that [1] describes 
Smalltalk as Strongly Typed, since Smalltalk is sometimes denigrated as 
being untyped / weakly typed. 
 From reviewing discussion forums this now makes sense, but I can only 
find one of scholarly reference that briefly mentions this [2].  The 
most enlightening is [3] which defines Type Strength as:

"A strongly typed language prevents any operation on the wrong type of 
data. In weakly typed languages there are ways to escape this 
restriction: type conversions"

meaning that getting a MNU is a form of Strong Typing since you can't 
make a Smalltalk object run a method that is not its own.  The problem 
appears to be that Strong Typing has been synonymous with Static Typing 
for a long time, and Static Typing strongly ties types to variables, 
except in Dynamically Typed languages, I think types can be considered 
independently from variables, in which case the definition of [3] has 
some merit, hence Smalltalk is Strongly Typed.

Sounds controversial, so I'm just hoping for some peer reviewed backup - 
but only you have something easily to hand. This is just a small thing I 
can just leave out if necessary.

cheers -ben

[1] http://www.squeak.org/Features/
[2] p15, 
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.35.7507&rep=rep1&type=pdf
[3] http://www.cs.kuleuven.ac.be/publicaties/rapporten/cw/CW415.pdf




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