Builtin math: ^ operator is left-associative

[0x005c]

The result of math '3^0.5^2' is currently:

~> math '3^0.5^2'
3

That mean, ^ operator is left-associative.
I think this is a bug because exponentiation operators in many languages are right-associative.

version:

~> fish --version
fish, version 3.0.2-1757-g47c0b5f9

[ridiculousfish]

Seems like a fun isolated bug to tackle for anyone interested. Thanks for filing!

[ankush-0x90]

Hie @ridiculousfish, I am really interested. Issue is really interesting and as I am new here I will need a little help. I have built it and I am looking into tinyexpr.cpp but not sure about changes..

[floam]

Easy fix. This is configurable in upstream TinyExpr and that author just likes the left-to-right because that's how spreadsheets do it. I think it will confuse people. Let's change it.

[floam]

If you want to give it a shot @asprazz, go ahead! Look at this code upstream:

https://github.com/codeplea/tinyexpr/blob/ffb0d41b13e5f8d318db95feb071c220c134fe70/tinyexpr.c#L415

See it has a compile time option for TE_POW_FROM_RIGHT? That provides a different version of the factor() function which has a while loop with different logic. Ours needs to be adapted to do the same thing. We've diverged and minimized our code from theirs a bit so there may be some adaptation required, it may be a fun practice to try to apply/translate the same differences you see to our codebase if you like!

[ankush-0x90]

@floam Thank you for clarification. I will be working on this now.. :) 💯

[ankush-0x90]

Hie @floam, Can you please look into my changes ?
I have removed a bunch of code saying => -a^b = -(a^b) as -2^2 = 4 not -4
Not sure about this tho :)
I have found an issue on upstream codeplea/tinyexpr#52

Hey @floam, Thank you for guiding me out. Btw I have created a PR (may be someone will) please review it whenever possible

[ArashPartow]

This issue was raised with the author a long time ago:

codeplea/tinyexpr#10 (comment)