Yeah empty parentheses for parameters-less function is the clear obvious way. Optional parenthesis for single parameter function is a wise choice. In fact, I read C# lambdas and they made really great design choices. I particularly like the statements lambda. How about doing it in Python with the set syntax and a little twist? The last item of the lambda set is the return value. Something like the following: (x, y) => {z = x + y, a = sqrt(z) - 10, a} The return value will be a. Basically if the last item is an expression, the return value will be the value of the expression. If the last item is an assignment statement, then the return value will be None. Only assignment statements and expressions are allowed. Other statements like for loop or with statement are too much anyways for lambda set. C# docs advise against using more than 3 statements in their statements lambda. Abdulla Sent from my iPhone
On 2 Oct 2021, at 8:33 PM, MRAB <python@mrabarnett.plus.com> wrote:
On 2021-10-02 08:59, Abdulla Al Kathiri wrote:
Let’s say I want to write a lambda function with no arguments that’s connected to a button in GUI coding, will blabla.connect(()=>print(“clicked”)) be used or will blabla.connect(=>print(“clicked”)) be used?
In the case of C#, the parentheses are optional if there's only one parameter, so:
() => ...
(x) => ... or x => ...
(x, y) => ...
(x, y, z) => ...
etc.
On 30 Sep 2021, at 7:53 PM, MRAB <python@mrabarnett.plus.com> wrote:
On 2021-09-30 07:21, Chris Angelico wrote:
On Thu, Sep 30, 2021 at 4:19 PM Steven D'Aprano <steve@pearwood.info> wrote:
>>> On Wed, Sep 29, 2021 at 02:09:03PM -0700, Guido van Rossum wrote: Over in typing-sig we're considering a new syntax for callable *types*, which would look like (int, int, str) -> float. A matching syntax for lambda would use a different arrow, e.g. (x, y, z) => x+y+z. >> I like arrow operators :-) >> But I fear that it will be too easy to misread `=>` as greater than or equal to, especially when skimming code. >> Assuming that they need to be different arrows, how do you feel about `->` for types and annotations, and `-->` for lambdas? Or `->>`? > JavaScript uses => for functions, and the confusion with ">=" doesn't seem to be a major problem with it. C# also uses "=>".
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