12 Jan
2009
12 Jan
'09
2:33 p.m.
How about using "let"s?
2009/1/12 Peter Verswyvelen
e = trace "e" op = (+) a1 = let f = (op (e 1)) in (f 10, f 100) a2 = let f = (\x -> op (e 1) x) in (f 10, f 100) a1 and a2 are operationally not the same: a1 will evaluate (e 1) once, a2
a3 = let f = (let y = e 1 in (\x -> op y x)) in (f 10, f 100)
e1 x = trace "e1" x e2 x = trace "e2" x op2 :: Int -> Int -> Int -> Int op2 x y z = x+10*y+100*z z1 = let f = (flip3_12 op2) (e1 1) (e2 2) in (f 3, f 4) z2 = let f = (flip3_13 op2) (e1 1) (e2 2) in (f 3, f 4) z3 = let f = (flip3_23 op2) (e1 1) (e2 2) in (f 3, f 4)
z1' = let f = (let y1 = e1 1; y2 = e2 2 in (\x -> op2 y2 y1 x)) in (f 3, f 4) -- Felipe.