use if instead of MacroTools

[JeffBezanson]

MacroTools' pattern matching is very slow, mostly due to using exceptions to signal no-match. This causes JuliaLang/julia#28221. Ideally MacroTools can be fixed too, but in the meantime it seems easier to switch this package to use simple tests like isexpr(ex, :call) && ex.args[1] == :+ instead of MacroTools. Of course that can be abstracted into iscall(ex, :+), etc. --- feel free to go nuts with that.

[ChrisRackauckas]

That was just added by #7 . We can revert the MacroTools changes as suggested. @devmotion ?

[YingboMa]

Can I give this issue a try?

[ChrisRackauckas]

Yes

[devmotion]

Yes seems like we should replace all occurrences of @capture that were added there. In my opinion the changes nevertheless were helpful to simplify the overall logic of MuladdMacro and added the subtraction handling, so I think we shouldn't just revert everything?

[MikeInnes]

Yes, all the utility functions like postwalk are fine, it's only calling @capture recursively that exposes this issue. It looks like the patterns are simple enough that explicit tests won't be a serious readability sacrifice.

[YingboMa]

Closed by #11

[MikeInnes]

FYI there's a fix for this in this PR – FluxML/MacroTools.jl#104

Would be nice to hear if you see an improvement in this case.