# CS计算机代考程序代写 database (*The following functions have been provided

(*The following functions have been provided

let rec map f xs = match xs with
| [] -> []
| x :: xt -> (f x)::(map f xt)

let rec foldl f a xs = match xs with
| [] -> a
| x :: xt -> foldl f (f a x) xt

let rec foldr f xs a = match xs with
| [] -> a
| x :: xt -> f x (foldr f xt a)

let rec rev lst = match lst with
| [] -> []
| x :: xt -> (rev xt) @ [x]

(*Implement these functions here*)
let mul_thresh lst thresh =
foldl
(fun (less, greater) x ->
if x < thresh then (x*less, greater) else (less, x*greater)) (1, 1) lst let multi_map f lst = map (fun x -> map f x) lst

type student_information =
{
name : string;
age : int;
gpa : float;
}

let update_database lst =
map
(fun (name, age, gpa) ->
{name=name; age=age; gpa=gpa;})
lst

let stalin_sort lst =
match lst with
| [] -> []
| x :: xt ->
let (_, lst) = (foldl
(fun (last_elem, lst) x ->
if x < last_elem then (last_elem, lst) else (x, lst@[x])) (x, []) lst) in lst let rec get_last_element lst = match lst with | [x] -> x
| _ :: xt -> get_last_element xt
| [] -> failwith “empty list has no elements”

let stalin_sort_right lst =
match lst with
| [] -> []
| _ ->
let x = get_last_element lst in
let (_, lst) = (foldr
(fun x (last_elem, lst) ->
if x > last_elem then (last_elem, lst)
else (x, x::lst))
lst
(x, [])) in
lst