[Python-ideas] Infix functions

[Andrew Barnert]

On Feb 25, 2014, at 15:02, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:

> Andrew Barnert wrote re Nick's concise lambda proposal:
> 
>>    data = using(:?.read(), open(path))
>>    buf = catch(:read_file(path), (FileNotFoundError, :'')
>>    b = cond(a, :1/a, :NaN)
> 
> This doesn't look like Python to me. It's too cryptic,
> especially with the '?'.

Yeah, that was my initial reaction to Nick's suggestion, but it's growing on me. Anyway, there's a separate thread on that, which is stalled while I gather use cases from real code. (The stdlib uses lambdas much less than user-level code does, but the docs are full of them...)

> If you think a colon in
> an except-expression looks too confusing, this would
> be far worse.

Personally, I have no problem with the colon in the except expression.

> Also, this kind of style would make it very easy to
> make subtle mistakes by getting the colons in the
> wrong places.

I'm not sure about that. I think in most cases, anywhere you put the colons wrong will be a SyntaxError. And most of the exceptions will be places where you should be using a full-syntax lambda or an out-of-line function anyway (e.g., in a dict mapping names to functions). But until I gather more examples I don't think I can argue that effectively.

> It's not quite the same thing as a Lisp macro, because
> the onus is on the caller to remember which arguments
> need to be quoted. In Lisp, the macro takes care of
> that.

Right, it's more like a regular function that takes sexprs, where it's up to the caller to quote them. But it's not even really a parallel with that, because this isn't quoting, it really is explicitly making a function.