On Sun, Nov 27, 2011 at 4:55 PM, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: >> My language combines generators and collection initializers, instead of >> creating a whole new syntax for comprehensions. >> >> [| for i in 0..10: for j in 0.10: yield return i * j |] > > Are we supposed to intuit what that means? > > Is | a token, or are the delimiters [| and |] ? > > Is there a difference between iterating over 0..10 and iterating over > what looks like a float 0.10? > > What is "yield return"?
I would assume that "yield return" is borrowed from C#, where it is basically equivalent to Python's yield statement. The advantage of using two keywords like that is that you can compare the statements "yield return foo" and "yield break", which is a bit clearer than comparing the equivalent "yield foo" and "return". Having to type out "yield return" in every comprehension seems a bit painful to me, but I can understand the approach: what is shown above is a full generator, not a single "generator expression" like we use in Python, so the statement keywords can't be omitted. It's trading off convenience for expressiveness (a bad trade-off IMO -- complex generators should be named, not anonymous). >> Lambdas and functions are the same thing in my language, so no need for >> a special keyword. > > That does not follow. Lambdas and def functions are the same thing in > Python, but Python requires a special keyword. I think the implication is that Unit has only one syntax for creating functions, which is lambda-style. In any case, why does Python require a special keyword? def is only used in a statement context, and lambda is only used in an expression context. Why not use the same keyword for both? I think the answer is historical: def came first, and when anonymous functions were added it didn't make sense to use the keyword "def" for them, because "def" implies a name being defined. Cheers, Ian -- http://mail.python.org/mailman/listinfo/python-list
