# Talk:2453: Excel Lambda

Another ghost cueball comic! You can see it in the last panel. 108.162.216.54 06:03, 22 April 2021 (UTC)

==> Is that something that has happened before? First time noticing it. Is it just a remnant of the sketching? Of doest it mean something? 162.158.93.213 13:21, 22 April 2021 (UTC)

Someone needs to add an explanation of the Lambda, and possibly how Excel is implementing it. (I suppose it would immediately be useful for cutting down common re-use within a formula line, though =IF(ISERR(FIND(":",A1)),A1,RIGHT(A1,LEN(A1)-FIND(":",A1))) is a trivial repeat of the FIND, once to check, then again to do, I often need to do far more nested things, check for being a value, repeat the FIND to deal with the LEFT, etc.) But it has the smell of being effectively a Macro in this instance. Which already seems to me to be the only way to run a *proper* Turing Machine in an Excel column without hitting Circular Reference issues.

Would it be a stretch to say that Turing's inability to prove if Cueball will stop is actually equivalent to the halting problem, except it is for Cueball and not an arbitrary Turing machine? I thought that was pretty funny. xTheBHox (talk) 11:30, 22 April 2021 (UTC)

Microsoft themselves claim that the addition of LAMBDA makes Excel turing-comlpete (see here: https://techcommunity.microsoft.com/t5/excel-blog/announcing-lambda-turn-excel-formulas-into-custom-functions/ba-p/1925546). Based on this comic, I would argue that it already was... 162.158.159.36 12:55, 22 April 2021 (UTC)