Excel supports reusable lambdas: https://support.microsoft.com/en-us/office/lambda-function-b...

Lambda support in Excel is quite new though, isn’t it? If the argument is “Excel is a proper programming language because it now supports lambdas”, that implies that for most of its existence it hasn’t been one

We've had VLOOKUP for a while.

That's a dictionary, not a general function.

it works well enough in discrete domains... it's literally the definition of a function - map something to something else.

Yes, a function is an injection [1].

Abstractly.

Listing all possible inputs with their outputs, and then doing a lookup....that's only sometimes useful.

[1] https://en.wikipedia.org/wiki/Injective_function

If we are talking Excel 365 after Feb 2022, then yes.

If we're talking Excel 2021, Excel 2019, etc. then no.

So Excel supports reusable Lambdas then? In the same way that many tools introduce new features and users need to upgrade versions to get them.

Yep, Excel 365 Version 2201+ support reusable lambdas.

Custom functions in excel

https://support.microsoft.com/en-us/office/create-custom-fun...

VBA