Typed Python?

Paul Prescod paul at prescod.net
Tue Jul 6 16:36:56 CEST 2004

Brett C. wrote:

>>To put it another way: Jarek complains that static typing would destroy 
>>the "fun". I think he means Python's flexibility. A type inferencer 
>>removes the need to declare types but a statically type-inferenced 
>>language is still statically typed. It will still be strict about type 
> This is not necessarily true.  While this is how Standard ML and
> friends use it, this is not how Python would use it.  Type inferencing
> can be used to infer types purely for performance reasons.

Well, yes, of course. But in the context of a question about STATIC TYPE 
CHECKING as opposed to: "Wouldn't it be great if Python were higher 
performance" I felt obliged to point out that there is no free lunch. 
The original poster asked for a steak with the consistency of fish and 
the flavour of bubble gum ice cream and they aren't going to get it: not 
from Starkiller, not from Haskell and not from Python 3000.

> And as just a general comment, type inferencing in Python without
> changing semantics is **very** limited.  

Right: and that's for performance reasons, not correctness reasons. 
Think about how much the semantics would have to change to be able to 
help with type correctness reliably.

  Paul Prescod

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