cannot call a proc without brackets

[Allosteric]

I understand that in Nim, you can call a proc without using brackets. Indeed, 
the following works fine:
    
    
    write stdout, "a" #== write(stdout, "a")
    
    #=>a
    

However, the followings fail.
    
    
    import strutils
    
    discard split "A,B,C" ',' #=> Error: invalid indentation
    
    
    
    proc add(x,y:int):int = x+y
    
    discard add 1, 2 #=> Error: type mismatch: got <int literal(1)>
    
    
    
    discard `+` 1, 2 #=> Error: invalid indentation
    

Is this a bug, or am I missing something?