How to write a higher order function that works on array of tuples

[general-rishkin]

The following (last two lines) throw up errors:

def foo(p: (a)->Bool, as: n=>a) -> Nat given (n|Ix, a) = 2

foo (\(x:String, y:Nat). x == "qwerty") [("w", 21), ("qwerty", 34), ("wert", 5)]  -- Does no work

foo (\(x, _). x == "qwerty") [("w", 21), ("qwerty", 34), ("wert", 5)]                     -- Does not work