Optimise indirection when getting the 'eq' or 'show' closure

[Matt Giuca]

When the 'eq' or 'show' functions are referenced, but not directly called, a new closure template is generated. This extra indirection is inefficient. For example, consider this code:

def get_eq() :: (a, a) -> Num:
    return eq

This generates the following Mars assembly code:

def get_eq(dict:a :: :Dict(a)) :: (a, a) -> Num:
    r = @ct:eq{dict:a}

def ct:eq{dict:a :: :Dict(a)}(x :: a, y :: a) :: Num:
    t = @:Dict:eq:ref(dict:a)
    r = t(x, y)

The value you get back from calling get_eq() is not the eq function for a -- it is a closure carrying around the type dict for a which, when called, looks up the eq function for a and calls it. This is more indirect than necessary. It should generate the following code:

def get_eq(dict:a :: :Dict(a)) :: (a, a) -> Num:
    r = @:Dict:eq:ref(dict:a)

[Matt Giuca (mgiuca)]

Fixed in trunk r1352.