That's made as shorter way to write code for SimplePlanes Funky Trees because that XML is pretty compressible, and also to remove constant parts where it can

Builtins aren't exact and only work for numbers

min and max can take arbitrary number of arguments

== works as = too

It also supports vectors of arbitrary length f((1,2,3))=>(f(1),f(2),f(3))

You can call expression (true?a:b)(1)=>a(1) but if it can't be optimized away it won't actually work in SP.

Of course you can combine two lines above, (true?a:b,b,c)(1)=>(a(1),b(1),c(1))

For multiline parser, newline is equivalent to semicolon; curly brackets {} are used for start and end of block and tabulation doesn't matters; because if i want to align some columns i mustn't be stopped by parser complaining about indents/dedends