Explanation for function composition and infix function application(PureScript) -
this code works findname :: string -> string -> addressbook -> boolean findname fname lname = not <<< null <<< filter findn findn :: entry -> boolean findn entry = entry.firstname == fname && entry.lastname == lname but not findname fname lname book = not <<< null <<< filter findn book again code works findname fname lname book= not $ null $ filter findn book and not findname fname lname = not null $ filter findn in short, because these different examples equivalent different placements of parentheses, code evaluated differently. f <<< g , f , g functions, equivalent \x -> f (g x) , whereas f x $ g y equivalent (f x) (g y) . whenever have infix symbol <<< , no other infix symbols, expressions left , right of symbol evaluated first, first example evaluated findname fname lname = ((not) <<< (null) <<< (filter findn)) , which book par...
