Question

Which of theese two alternatives do you find yourself using most often, and which is more ‘idiomatic’?

1. f arg (obj.DoStuff())
2. f arg <| obj.DoStuff()

Answer 1

Overall, I don’t know that one or the other is more idiomatic.

Personally, the only time I use <| is with ‘raise’:

raise <| new FooException('blah') 

Apart from that, I always use parens. Note that since most F# code uses curried functions, this does not typically imply any ‘extra’ parens:

f arg (g x y) 

It’s when you get into non-curried functions and constructors and whatnot that it starts getting less pretty:

f arg (g(x,y)) 

We will probably at least consider changing the F# languages rules so that high-precedence applications bind even more tightly; right now

f g() 

parses like

f g () 

but a lot of people would like it to parse as

f (g()) 

(the motivating case in the original question). If you have a strong opinion about this, leave a comment on this response.