Optimize stdlib (#215)

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Radosław Rowicki 2020-02-07 19:51:12 +01:00 committed by GitHub
parent 34c10e1518
commit 13bc821211
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2 changed files with 91 additions and 84 deletions

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@ -19,18 +19,28 @@ namespace List =
[x] => Some(x)
_::t => last(t)
function drop_last(l : list('a)) : option(list('a)) = switch(l)
[] => None
_ => Some(drop_last_unsafe(l))
function drop_last_unsafe(l : list('a)) : list('a) = switch(l)
[_] => []
h::t => h::drop_last_unsafe(t)
[] => abort("drop_last_unsafe: list empty")
function find(p : 'a => bool, l : list('a)) : option('a) = switch(l)
[] => None
h::t => if(p(h)) Some(h) else find(p, t)
function find_indices(p : 'a => bool, l : list('a)) : list(int) = find_indices_(p, l, 0, [])
function find_indices(p : 'a => bool, l : list('a)) : list(int) = find_indices_(p, l, 0)
private function find_indices_( p : 'a => bool
, l : list('a)
, n : int
, acc : list(int)
) : list(int) = switch(l)
[] => reverse(acc)
h::t => find_indices_(p, t, n+1, if(p(h)) n::acc else acc)
[] => []
h::t =>
let rest = find_indices_(p, t, n+1)
if(p(h)) n::rest else rest
function nth(n : int, l : list('a)) : option('a) =
switch(l)
@ -52,39 +62,40 @@ namespace List =
function from_to(a : int, b : int) : list(int) = [a..b]
function from_to_step(a : int, b : int, s : int) : list(int) = from_to_step_(a, b, s, [])
private function from_to_step_(a, b, s, acc) =
if (a > b) reverse(acc) else from_to_step_(a + s, b, s, a :: acc)
function from_to_step(a : int, b : int, s : int) : list(int) =
from_to_step_(a, b - (b-a) mod s, s, [])
private function from_to_step_(a : int, b : int, s : int, acc : list(int)) : list(int) =
if(b < a) acc
else from_to_step_(a, b - s, s, b::acc)
/* Unsafe. Replaces `n`th element of `l` with `e`. Crashes on over/underflow */
function replace_at(n : int, e : 'a, l : list('a)) : list('a) =
if(n<0) abort("insert_at underflow") else replace_at_(n, e, l, [])
private function replace_at_(n : int, e : 'a, l : list('a), acc : list('a)) : list('a) =
if(n<0) abort("insert_at underflow") else replace_at_(n, e, l)
private function replace_at_(n : int, e : 'a, l : list('a)) : list('a) =
switch(l)
[] => abort("replace_at overflow")
h::t => if (n == 0) reverse(e::acc) ++ t
else replace_at_(n-1, e, t, h::acc)
h::t => if (n == 0) e::t
else h::replace_at_(n-1, e, t)
/* Unsafe. Adds `e` to `l` to be its `n`th element. Crashes on over/underflow */
function insert_at(n : int, e : 'a, l : list('a)) : list('a) =
if(n<0) abort("insert_at underflow") else insert_at_(n, e, l, [])
private function insert_at_(n : int, e : 'a, l : list('a), acc : list('a)) : list('a) =
if (n == 0) reverse(e::acc) ++ l
if(n<0) abort("insert_at underflow") else insert_at_(n, e, l)
private function insert_at_(n : int, e : 'a, l : list('a)) : list('a) =
if (n == 0) e::l
else switch(l)
[] => abort("insert_at overflow")
h::t => insert_at_(n-1, e, t, h::acc)
h::t => h::insert_at_(n-1, e, t)
function insert_by(cmp : (('a, 'a) => bool), x : 'a, l : list('a)) : list('a) =
insert_by_(cmp, x, l, [])
private function insert_by_(cmp : (('a, 'a) => bool), x : 'a, l : list('a), acc : list('a)) : list('a) =
switch(l)
[] => reverse(x::acc)
[] => [x]
h::t =>
if(cmp(x, h)) // x < h
reverse(acc) ++ (x::l)
x::l
else
insert_by_(cmp, x, t, h::acc)
h::insert_by(cmp, x, t)
function foldr(cons : ('a, 'b) => 'b, nil : 'b, l : list('a)) : 'b = switch(l)
@ -102,43 +113,46 @@ namespace List =
f(e)
foreach(l', f)
function reverse(l : list('a)) : list('a) = foldl((lst, el) => el :: lst, [], l)
function reverse(l : list('a)) : list('a) = reverse_(l, [])
private function reverse_(l : list('a), acc : list('a)) : list('a) = switch(l)
[] => acc
h::t => reverse_(t, h::acc)
function map(f : 'a => 'b, l : list('a)) : list('b) = map_(f, l, [])
private function map_(f : 'a => 'b, l : list('a), acc : list('b)) : list('b) = switch(l)
[] => reverse(acc)
h::t => map_(f, t, f(h)::acc)
function map(f : 'a => 'b, l : list('a)) : list('b) = switch(l)
[] => []
h::t => f(h)::map(f, t)
function flat_map(f : 'a => list('b), l : list('a)) : list('b) =
ListInternal.flat_map(f, l)
function filter(p : 'a => bool, l : list('a)) : list('a) = filter_(p, l, [])
private function filter_(p : 'a => bool, l : list('a), acc : list('a)) : list('a) = switch(l)
[] => reverse(acc)
h::t => filter_(p, t, if(p(h)) h::acc else acc)
function filter(p : 'a => bool, l : list('a)) : list('a) = switch(l)
[] => []
h::t =>
let rest = filter(p, t)
if(p(h)) h::rest else rest
/* Take `n` first elements */
/* Take up to `n` first elements */
function take(n : int, l : list('a)) : list('a) =
if(n < 0) abort("Take negative number of elements") else take_(n, l, [])
private function take_(n : int, l : list('a), acc : list('a)) : list('a) =
if(n == 0) reverse(acc)
else switch(l)
[] => reverse(acc)
h::t => take_(n-1, t, h::acc)
/* Drop `n` first elements */
function drop(n : int, l : list('a)) : list('a) =
if(n < 0) abort("Drop negative number of elements")
elif (n == 0) l
if(n < 0) abort("Take negative number of elements") else take_(n, l)
private function take_(n : int, l : list('a)) : list('a) =
if(n == 0) []
else switch(l)
[] => []
h::t => drop(n-1, t)
h::t => h::take_(n-1, t)
/* Drop up to `n` first elements */
function drop(n : int, l : list('a)) : list('a) =
if(n < 0) abort("Drop negative number of elements") else drop_(n, l)
private function drop_(n : int, l : list('a)) : list('a) =
if (n == 0) l
else switch(l)
[] => []
h::t => drop_(n-1, t)
/* Get the longest prefix of a list in which every element matches predicate `p` */
function take_while(p : 'a => bool, l : list('a)) : list('a) = take_while_(p, l, [])
private function take_while_(p : 'a => bool, l : list('a), acc : list('a)) : list('a) = switch(l)
[] => reverse(acc)
h::t => if(p(h)) take_while_(p, t, h::acc) else reverse(acc)
function take_while(p : 'a => bool, l : list('a)) : list('a) = switch(l)
[] => []
h::t => if(p(h)) h::take_while(p, t) else []
/* Drop elements from `l` until `p` holds */
function drop_while(p : 'a => bool, l : list('a)) : list('a) = switch(l)
@ -146,17 +160,15 @@ namespace List =
h::t => if(p(h)) drop_while(p, t) else l
/* Splits list into two lists of elements that respectively match and don't match predicate `p` */
function partition(p : 'a => bool, l : list('a)) : (list('a) * list('a)) = partition_(p, l, [], [])
private function partition_( p : 'a => bool
, l : list('a)
, acc_t : list('a)
, acc_f : list('a)
) : (list('a) * list('a)) = switch(l)
[] => (reverse(acc_t), reverse(acc_f))
h::t => if(p(h)) partition_(p, t, h::acc_t, acc_f) else partition_(p, t, acc_t, h::acc_f)
function partition(p : 'a => bool, l : list('a)) : (list('a) * list('a)) = switch(l)
[] => ([], [])
h::t =>
let (l, r) = partition(p, t)
if(p(h)) (h::l, r) else (l, h::r)
function flatten(ll : list(list('a))) : list('a) = foldr((l1, l2) => l1 ++ l2, [], ll)
function flatten(l : list(list('a))) : list('a) = switch(l)
[] => []
h::t => h ++ flatten(t)
function all(p : 'a => bool, l : list('a)) : bool = switch(l)
[] => true
@ -172,25 +184,21 @@ namespace List =
/* Zips two list by applying bimapping function on respective elements. Drops longer tail. */
function zip_with(f : ('a, 'b) => 'c, l1 : list('a), l2 : list('b)) : list('c) = zip_with_(f, l1, l2, [])
private function zip_with_( f : ('a, 'b) => 'c
private function zip_with( f : ('a, 'b) => 'c
, l1 : list('a)
, l2 : list('b)
, acc : list('c)
) : list('c) = switch ((l1, l2))
(h1::t1, h2::t2) => zip_with_(f, t1, t2, f(h1, h2)::acc)
_ => reverse(acc)
(h1::t1, h2::t2) => f(h1, h2)::zip_with(f, t1, t2)
_ => []
/* Zips two lists into list of pairs. Drops longer tail. */
function zip(l1 : list('a), l2 : list('b)) : list('a * 'b) = zip_with((a, b) => (a, b), l1, l2)
function unzip(l : list('a * 'b)) : list('a) * list('b) = unzip_(l, [], [])
private function unzip_( l : list('a * 'b)
, acc_l : list('a)
, acc_r : list('b)
) : (list('a) * list('b)) = switch(l)
[] => (reverse(acc_l), reverse(acc_r))
(left, right)::t => unzip_(t, left::acc_l, right::acc_r)
function unzip(l : list('a * 'b)) : (list('a) * list('b)) = switch(l)
[] => ([], [])
(h1, h2)::t =>
let (t1, t2) = unzip(t)
(h1::t1, h2::t2)
// TODO: Improve?
@ -200,15 +208,14 @@ namespace List =
(lesser, bigger) => sort(lesser_cmp, lesser) ++ h::sort(lesser_cmp, bigger)
function intersperse(delim : 'a, l : list('a)) : list('a) = intersperse_(delim, l, [])
private function intersperse_(delim : 'a, l : list('a), acc : list('a)) : list('a) = switch(l)
[] => reverse(acc)
[e] => reverse(e::acc)
h::t => intersperse_(delim, t, delim::h::acc)
function intersperse(delim : 'a, l : list('a)) : list('a) = switch(l)
[] => []
[e] => [e]
h::t => h::delim::intersperse(delim, t)
function enumerate(l : list('a)) : list(int * 'a) = enumerate_(l, 0, [])
private function enumerate_(l : list('a), n : int, acc : list(int * 'a)) : list(int * 'a) = switch(l)
[] => reverse(acc)
h::t => enumerate_(t, n + 1, (n, h)::acc)
function enumerate(l : list('a)) : list(int * 'a) = enumerate_(l, 0)
private function enumerate_(l : list('a), n : int) : list(int * 'a) = switch(l)
[] => []
h::t => (n, h)::enumerate_(t, n + 1)

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@ -53,17 +53,17 @@ namespace Option =
None => []
Some(x) => [x]
function filter_options(l : list(option('a))) : list('a) = filter_options_(l, [])
private function filter_options_(l : list (option('a)), acc : list('a)) : list('a) = switch(l)
[] => List.reverse(acc)
None::t => filter_options_(t, acc)
Some(x)::t => filter_options_(t, x::acc)
function filter_options(l : list(option('a))) : list('a) = switch(l)
[] => []
None::t => filter_options(t)
Some(x)::t => x::filter_options(t)
function seq_options(l : list (option('a))) : option (list('a)) = seq_options_(l, [])
private function seq_options_(l : list (option('a)), acc : list('a)) : option(list('a)) = switch(l)
[] => Some(List.reverse(acc))
None::t => None
Some(x)::t => seq_options_(t, x::acc)
function seq_options(l : list (option('a))) : option (list('a)) = switch(l)
[] => Some([])
None::_ => None
Some(x)::t => switch(seq_options(t))
None => None
Some(st) => Some(x::st)
function choose(o1 : option('a), o2 : option('a)) : option('a) =