Fix MGA (Malagasy Ariary) to be a zero-decimal currency

[mapreal19]

According to Stripe's documentation (https://docs.stripe.com/currencies#zero-decimal), MGA is included in their list of zero-decimal currencies, and this change ensures the Money gem correctly formats MGA amounts without decimal places.

Also from the Wikipedia entry:

It is notionally subdivided into 5 iraimbilanja and is one of only two non-decimal currencies currently circulating (the other is the Mauritanian ouguiya). The names ariary and iraimbilanja derive from the pre-colonial currency, with ariary (from the Spanish word "real") being the name for a silver dollar. Iraimbilanja means "one iron weight" and was the name of an old coin worth 1⁄5 of an ariary. However, as of May 2023, the unit is effectively obsolete since the iraimbilanja has practically no purchasing power, and the coins have fallen into disuse.

[mapreal19]

@cade can you check this one out? Thoughts?

[cade]

Yep. Thanks for the Stripe/Wikipedia links!

[mapreal19]

@cade thanks!

[RemyDuijkeren]

Where is the proof that since May 2023, the 1/5 unit is effectively obsolete?

According to ISO-4217 it is still valid. The fact that Stripe treats it as a zero-decimal currency should not trigger this change? Wiki mention it but without any reference.

[mapreal19]

@RemyDuijkeren true that wiki entry doesn't have a proper reference. Should we revert this change then? I couldn't find any other reliable information about this

[RemyDuijkeren]

@mapreal19 I don't use RubyMoney so I can't say anything about which direction to take (I maintain the .NET counterpart, so there for my interest in RubyMoney).

I also couldn't find any reliable information about this, so I personally lean more on what ISO is saying.

[mapreal19]

@cade what's your opinion on this?

[cade]

Firstly, I absolutely do not consider myself the final source of truth for the RubyMoney gem's formatting decisions. I have also experienced first hand situations where lagging ISO standard updates in other areas cause real bugs/errors/pain.

That said, I tried to go down the Wikipedia article's edit history rabbit hole. There's an edit at least as far back as 2021 claiming that the iraimbilanja is "effectively obsolete." I have no first-hand experience with this currency, and cannot confidently attest to the truth of this claim. However, I do generally trust Wikipedia references for currency details, even if there's not extensive citations.

I have no horse in this race, but I'm inclined to personally lean into seemingly real-world usage (as it appears Stripe has done) over dying on the ISO hill until the standard is updated. That said, if anyone else disagrees and reverts this, I will have zero objections. 🤷

[RemyDuijkeren]

My personal experience is that when people talk about 'this is not being used anymore' they often talk about cash transactions. Like the 1- and 2-cent EUR in The Netherlands.

But the fact that Stripe is not doing it for financial transactions is a strong indicator that maybe it is really not used overall anymore.