pre-PEP: Simple Thunks

[Steven Bethard]

Greg Ewing wrote:
> Brian Sabbey wrote:
> 
>> do f in with_file('file.txt'):
>>     print f.read()
> 
> 
> I don't like this syntax. Try to read it as an English sentence:
> "Do f in with file 'file.txt'". Say what???
> 
> To sound right it would have to be something like
> 
>   with_file('file.txt') as f do:
>     print f.read()
> 

This is still strange since f is the arguments the thunk was called 
with, e.g. the current syntax is basically:

     do <unpack_list> in <returnval> = <callable>(<params>):
         <code>

I don't really know a more readable sequence of keywords, though someone 
suggested 'with' and 'from', which might read something like:

     with <unpack_list> from <callable>(<params>):
         <code>

which looks okay to me, though I'm not sure that 'with' makes it clear 
that this is not a normal block...  I also find readability problems 
when I try to stick <returnval> back in.

One of the other issues is that, with the current proposal, the thunk 
can be called multiple times within a function, so the keywords have to 
make sense both with a single iteration interpretation and a multiple 
iteration interpretation...  Makes it even harder...

STeVe