671 lines
19 KiB
Nix
671 lines
19 KiB
Nix
# General list operations.
|
|
|
|
{ lib }:
|
|
let
|
|
inherit (lib.strings) toInt;
|
|
inherit (lib.trivial) compare min;
|
|
in
|
|
rec {
|
|
|
|
inherit (builtins) head tail length isList elemAt concatLists filter elem genList map;
|
|
|
|
/* Create a list consisting of a single element. `singleton x` is
|
|
sometimes more convenient with respect to indentation than `[x]`
|
|
when x spans multiple lines.
|
|
|
|
Type: singleton :: a -> [a]
|
|
|
|
Example:
|
|
singleton "foo"
|
|
=> [ "foo" ]
|
|
*/
|
|
singleton = x: [x];
|
|
|
|
/* Apply the function to each element in the list. Same as `map`, but arguments
|
|
flipped.
|
|
|
|
Type: forEach :: [a] -> (a -> b) -> [b]
|
|
|
|
Example:
|
|
forEach [ 1 2 ] (x:
|
|
toString x
|
|
)
|
|
=> [ "1" "2" ]
|
|
*/
|
|
forEach = xs: f: map f xs;
|
|
|
|
/* “right fold” a binary function `op` between successive elements of
|
|
`list` with `nul' as the starting value, i.e.,
|
|
`foldr op nul [x_1 x_2 ... x_n] == op x_1 (op x_2 ... (op x_n nul))`.
|
|
|
|
Type: foldr :: (a -> b -> b) -> b -> [a] -> b
|
|
|
|
Example:
|
|
concat = foldr (a: b: a + b) "z"
|
|
concat [ "a" "b" "c" ]
|
|
=> "abcz"
|
|
# different types
|
|
strange = foldr (int: str: toString (int + 1) + str) "a"
|
|
strange [ 1 2 3 4 ]
|
|
=> "2345a"
|
|
*/
|
|
foldr = op: nul: list:
|
|
let
|
|
len = length list;
|
|
fold' = n:
|
|
if n == len
|
|
then nul
|
|
else op (elemAt list n) (fold' (n + 1));
|
|
in fold' 0;
|
|
|
|
/* `fold` is an alias of `foldr` for historic reasons */
|
|
# FIXME(Profpatsch): deprecate?
|
|
fold = foldr;
|
|
|
|
|
|
/* “left fold”, like `foldr`, but from the left:
|
|
`foldl op nul [x_1 x_2 ... x_n] == op (... (op (op nul x_1) x_2) ... x_n)`.
|
|
|
|
Type: foldl :: (b -> a -> b) -> b -> [a] -> b
|
|
|
|
Example:
|
|
lconcat = foldl (a: b: a + b) "z"
|
|
lconcat [ "a" "b" "c" ]
|
|
=> "zabc"
|
|
# different types
|
|
lstrange = foldl (str: int: str + toString (int + 1)) "a"
|
|
lstrange [ 1 2 3 4 ]
|
|
=> "a2345"
|
|
*/
|
|
foldl = op: nul: list:
|
|
let
|
|
foldl' = n:
|
|
if n == -1
|
|
then nul
|
|
else op (foldl' (n - 1)) (elemAt list n);
|
|
in foldl' (length list - 1);
|
|
|
|
/* Strict version of `foldl`.
|
|
|
|
The difference is that evaluation is forced upon access. Usually used
|
|
with small whole results (in contrast with lazily-generated list or large
|
|
lists where only a part is consumed.)
|
|
|
|
Type: foldl' :: (b -> a -> b) -> b -> [a] -> b
|
|
*/
|
|
foldl' = builtins.foldl' or foldl;
|
|
|
|
/* Map with index starting from 0
|
|
|
|
Type: imap0 :: (int -> a -> b) -> [a] -> [b]
|
|
|
|
Example:
|
|
imap0 (i: v: "${v}-${toString i}") ["a" "b"]
|
|
=> [ "a-0" "b-1" ]
|
|
*/
|
|
imap0 = f: list: genList (n: f n (elemAt list n)) (length list);
|
|
|
|
/* Map with index starting from 1
|
|
|
|
Type: imap1 :: (int -> a -> b) -> [a] -> [b]
|
|
|
|
Example:
|
|
imap1 (i: v: "${v}-${toString i}") ["a" "b"]
|
|
=> [ "a-1" "b-2" ]
|
|
*/
|
|
imap1 = f: list: genList (n: f (n + 1) (elemAt list n)) (length list);
|
|
|
|
/* Map and concatenate the result.
|
|
|
|
Type: concatMap :: (a -> [b]) -> [a] -> [b]
|
|
|
|
Example:
|
|
concatMap (x: [x] ++ ["z"]) ["a" "b"]
|
|
=> [ "a" "z" "b" "z" ]
|
|
*/
|
|
concatMap = builtins.concatMap or (f: list: concatLists (map f list));
|
|
|
|
/* Flatten the argument into a single list; that is, nested lists are
|
|
spliced into the top-level lists.
|
|
|
|
Example:
|
|
flatten [1 [2 [3] 4] 5]
|
|
=> [1 2 3 4 5]
|
|
flatten 1
|
|
=> [1]
|
|
*/
|
|
flatten = x:
|
|
if isList x
|
|
then concatMap (y: flatten y) x
|
|
else [x];
|
|
|
|
/* Remove elements equal to 'e' from a list. Useful for buildInputs.
|
|
|
|
Type: remove :: a -> [a] -> [a]
|
|
|
|
Example:
|
|
remove 3 [ 1 3 4 3 ]
|
|
=> [ 1 4 ]
|
|
*/
|
|
remove =
|
|
# Element to remove from the list
|
|
e: filter (x: x != e);
|
|
|
|
/* Find the sole element in the list matching the specified
|
|
predicate, returns `default` if no such element exists, or
|
|
`multiple` if there are multiple matching elements.
|
|
|
|
Type: findSingle :: (a -> bool) -> a -> a -> [a] -> a
|
|
|
|
Example:
|
|
findSingle (x: x == 3) "none" "multiple" [ 1 3 3 ]
|
|
=> "multiple"
|
|
findSingle (x: x == 3) "none" "multiple" [ 1 3 ]
|
|
=> 3
|
|
findSingle (x: x == 3) "none" "multiple" [ 1 9 ]
|
|
=> "none"
|
|
*/
|
|
findSingle =
|
|
# Predicate
|
|
pred:
|
|
# Default value to return if element was not found.
|
|
default:
|
|
# Default value to return if more than one element was found
|
|
multiple:
|
|
# Input list
|
|
list:
|
|
let found = filter pred list; len = length found;
|
|
in if len == 0 then default
|
|
else if len != 1 then multiple
|
|
else head found;
|
|
|
|
/* Find the first element in the list matching the specified
|
|
predicate or return `default` if no such element exists.
|
|
|
|
Type: findFirst :: (a -> bool) -> a -> [a] -> a
|
|
|
|
Example:
|
|
findFirst (x: x > 3) 7 [ 1 6 4 ]
|
|
=> 6
|
|
findFirst (x: x > 9) 7 [ 1 6 4 ]
|
|
=> 7
|
|
*/
|
|
findFirst =
|
|
# Predicate
|
|
pred:
|
|
# Default value to return
|
|
default:
|
|
# Input list
|
|
list:
|
|
let found = filter pred list;
|
|
in if found == [] then default else head found;
|
|
|
|
/* Return true if function `pred` returns true for at least one
|
|
element of `list`.
|
|
|
|
Type: any :: (a -> bool) -> [a] -> bool
|
|
|
|
Example:
|
|
any isString [ 1 "a" { } ]
|
|
=> true
|
|
any isString [ 1 { } ]
|
|
=> false
|
|
*/
|
|
any = builtins.any or (pred: foldr (x: y: if pred x then true else y) false);
|
|
|
|
/* Return true if function `pred` returns true for all elements of
|
|
`list`.
|
|
|
|
Type: all :: (a -> bool) -> [a] -> bool
|
|
|
|
Example:
|
|
all (x: x < 3) [ 1 2 ]
|
|
=> true
|
|
all (x: x < 3) [ 1 2 3 ]
|
|
=> false
|
|
*/
|
|
all = builtins.all or (pred: foldr (x: y: if pred x then y else false) true);
|
|
|
|
/* Count how many elements of `list` match the supplied predicate
|
|
function.
|
|
|
|
Type: count :: (a -> bool) -> [a] -> int
|
|
|
|
Example:
|
|
count (x: x == 3) [ 3 2 3 4 6 ]
|
|
=> 2
|
|
*/
|
|
count =
|
|
# Predicate
|
|
pred: foldl' (c: x: if pred x then c + 1 else c) 0;
|
|
|
|
/* Return a singleton list or an empty list, depending on a boolean
|
|
value. Useful when building lists with optional elements
|
|
(e.g. `++ optional (system == "i686-linux") firefox').
|
|
|
|
Type: optional :: bool -> a -> [a]
|
|
|
|
Example:
|
|
optional true "foo"
|
|
=> [ "foo" ]
|
|
optional false "foo"
|
|
=> [ ]
|
|
*/
|
|
optional = cond: elem: if cond then [elem] else [];
|
|
|
|
/* Return a list or an empty list, depending on a boolean value.
|
|
|
|
Type: optionals :: bool -> [a] -> [a]
|
|
|
|
Example:
|
|
optionals true [ 2 3 ]
|
|
=> [ 2 3 ]
|
|
optionals false [ 2 3 ]
|
|
=> [ ]
|
|
*/
|
|
optionals =
|
|
# Condition
|
|
cond:
|
|
# List to return if condition is true
|
|
elems: if cond then elems else [];
|
|
|
|
|
|
/* If argument is a list, return it; else, wrap it in a singleton
|
|
list. If you're using this, you should almost certainly
|
|
reconsider if there isn't a more "well-typed" approach.
|
|
|
|
Example:
|
|
toList [ 1 2 ]
|
|
=> [ 1 2 ]
|
|
toList "hi"
|
|
=> [ "hi "]
|
|
*/
|
|
toList = x: if isList x then x else [x];
|
|
|
|
/* Return a list of integers from `first' up to and including `last'.
|
|
|
|
Type: range :: int -> int -> [int]
|
|
|
|
Example:
|
|
range 2 4
|
|
=> [ 2 3 4 ]
|
|
range 3 2
|
|
=> [ ]
|
|
*/
|
|
range =
|
|
# First integer in the range
|
|
first:
|
|
# Last integer in the range
|
|
last:
|
|
if first > last then
|
|
[]
|
|
else
|
|
genList (n: first + n) (last - first + 1);
|
|
|
|
/* Splits the elements of a list in two lists, `right` and
|
|
`wrong`, depending on the evaluation of a predicate.
|
|
|
|
Type: (a -> bool) -> [a] -> { right :: [a], wrong :: [a] }
|
|
|
|
Example:
|
|
partition (x: x > 2) [ 5 1 2 3 4 ]
|
|
=> { right = [ 5 3 4 ]; wrong = [ 1 2 ]; }
|
|
*/
|
|
partition = builtins.partition or (pred:
|
|
foldr (h: t:
|
|
if pred h
|
|
then { right = [h] ++ t.right; wrong = t.wrong; }
|
|
else { right = t.right; wrong = [h] ++ t.wrong; }
|
|
) { right = []; wrong = []; });
|
|
|
|
/* Splits the elements of a list into many lists, using the return value of a predicate.
|
|
Predicate should return a string which becomes keys of attrset `groupBy' returns.
|
|
|
|
`groupBy'` allows to customise the combining function and initial value
|
|
|
|
Example:
|
|
groupBy (x: boolToString (x > 2)) [ 5 1 2 3 4 ]
|
|
=> { true = [ 5 3 4 ]; false = [ 1 2 ]; }
|
|
groupBy (x: x.name) [ {name = "icewm"; script = "icewm &";}
|
|
{name = "xfce"; script = "xfce4-session &";}
|
|
{name = "icewm"; script = "icewmbg &";}
|
|
{name = "mate"; script = "gnome-session &";}
|
|
]
|
|
=> { icewm = [ { name = "icewm"; script = "icewm &"; }
|
|
{ name = "icewm"; script = "icewmbg &"; } ];
|
|
mate = [ { name = "mate"; script = "gnome-session &"; } ];
|
|
xfce = [ { name = "xfce"; script = "xfce4-session &"; } ];
|
|
}
|
|
|
|
groupBy' builtins.add 0 (x: boolToString (x > 2)) [ 5 1 2 3 4 ]
|
|
=> { true = 12; false = 3; }
|
|
*/
|
|
groupBy' = op: nul: pred: lst:
|
|
foldl' (r: e:
|
|
let
|
|
key = pred e;
|
|
in
|
|
r // { ${key} = op (r.${key} or nul) e; }
|
|
) {} lst;
|
|
|
|
groupBy = groupBy' (sum: e: sum ++ [e]) [];
|
|
|
|
/* Merges two lists of the same size together. If the sizes aren't the same
|
|
the merging stops at the shortest. How both lists are merged is defined
|
|
by the first argument.
|
|
|
|
Type: zipListsWith :: (a -> b -> c) -> [a] -> [b] -> [c]
|
|
|
|
Example:
|
|
zipListsWith (a: b: a + b) ["h" "l"] ["e" "o"]
|
|
=> ["he" "lo"]
|
|
*/
|
|
zipListsWith =
|
|
# Function to zip elements of both lists
|
|
f:
|
|
# First list
|
|
fst:
|
|
# Second list
|
|
snd:
|
|
genList
|
|
(n: f (elemAt fst n) (elemAt snd n)) (min (length fst) (length snd));
|
|
|
|
/* Merges two lists of the same size together. If the sizes aren't the same
|
|
the merging stops at the shortest.
|
|
|
|
Type: zipLists :: [a] -> [b] -> [{ fst :: a, snd :: b}]
|
|
|
|
Example:
|
|
zipLists [ 1 2 ] [ "a" "b" ]
|
|
=> [ { fst = 1; snd = "a"; } { fst = 2; snd = "b"; } ]
|
|
*/
|
|
zipLists = zipListsWith (fst: snd: { inherit fst snd; });
|
|
|
|
/* Reverse the order of the elements of a list.
|
|
|
|
Type: reverseList :: [a] -> [a]
|
|
|
|
Example:
|
|
|
|
reverseList [ "b" "o" "j" ]
|
|
=> [ "j" "o" "b" ]
|
|
*/
|
|
reverseList = xs:
|
|
let l = length xs; in genList (n: elemAt xs (l - n - 1)) l;
|
|
|
|
/* Depth-First Search (DFS) for lists `list != []`.
|
|
|
|
`before a b == true` means that `b` depends on `a` (there's an
|
|
edge from `b` to `a`).
|
|
|
|
Example:
|
|
listDfs true hasPrefix [ "/home/user" "other" "/" "/home" ]
|
|
== { minimal = "/"; # minimal element
|
|
visited = [ "/home/user" ]; # seen elements (in reverse order)
|
|
rest = [ "/home" "other" ]; # everything else
|
|
}
|
|
|
|
listDfs true hasPrefix [ "/home/user" "other" "/" "/home" "/" ]
|
|
== { cycle = "/"; # cycle encountered at this element
|
|
loops = [ "/" ]; # and continues to these elements
|
|
visited = [ "/" "/home/user" ]; # elements leading to the cycle (in reverse order)
|
|
rest = [ "/home" "other" ]; # everything else
|
|
|
|
*/
|
|
listDfs = stopOnCycles: before: list:
|
|
let
|
|
dfs' = us: visited: rest:
|
|
let
|
|
c = filter (x: before x us) visited;
|
|
b = partition (x: before x us) rest;
|
|
in if stopOnCycles && (length c > 0)
|
|
then { cycle = us; loops = c; inherit visited rest; }
|
|
else if length b.right == 0
|
|
then # nothing is before us
|
|
{ minimal = us; inherit visited rest; }
|
|
else # grab the first one before us and continue
|
|
dfs' (head b.right)
|
|
([ us ] ++ visited)
|
|
(tail b.right ++ b.wrong);
|
|
in dfs' (head list) [] (tail list);
|
|
|
|
/* Sort a list based on a partial ordering using DFS. This
|
|
implementation is O(N^2), if your ordering is linear, use `sort`
|
|
instead.
|
|
|
|
`before a b == true` means that `b` should be after `a`
|
|
in the result.
|
|
|
|
Example:
|
|
|
|
toposort hasPrefix [ "/home/user" "other" "/" "/home" ]
|
|
== { result = [ "/" "/home" "/home/user" "other" ]; }
|
|
|
|
toposort hasPrefix [ "/home/user" "other" "/" "/home" "/" ]
|
|
== { cycle = [ "/home/user" "/" "/" ]; # path leading to a cycle
|
|
loops = [ "/" ]; } # loops back to these elements
|
|
|
|
toposort hasPrefix [ "other" "/home/user" "/home" "/" ]
|
|
== { result = [ "other" "/" "/home" "/home/user" ]; }
|
|
|
|
toposort (a: b: a < b) [ 3 2 1 ] == { result = [ 1 2 3 ]; }
|
|
|
|
*/
|
|
toposort = before: list:
|
|
let
|
|
dfsthis = listDfs true before list;
|
|
toporest = toposort before (dfsthis.visited ++ dfsthis.rest);
|
|
in
|
|
if length list < 2
|
|
then # finish
|
|
{ result = list; }
|
|
else if dfsthis ? cycle
|
|
then # there's a cycle, starting from the current vertex, return it
|
|
{ cycle = reverseList ([ dfsthis.cycle ] ++ dfsthis.visited);
|
|
inherit (dfsthis) loops; }
|
|
else if toporest ? cycle
|
|
then # there's a cycle somewhere else in the graph, return it
|
|
toporest
|
|
# Slow, but short. Can be made a bit faster with an explicit stack.
|
|
else # there are no cycles
|
|
{ result = [ dfsthis.minimal ] ++ toporest.result; };
|
|
|
|
/* Sort a list based on a comparator function which compares two
|
|
elements and returns true if the first argument is strictly below
|
|
the second argument. The returned list is sorted in an increasing
|
|
order. The implementation does a quick-sort.
|
|
|
|
Example:
|
|
sort (a: b: a < b) [ 5 3 7 ]
|
|
=> [ 3 5 7 ]
|
|
*/
|
|
sort = builtins.sort or (
|
|
strictLess: list:
|
|
let
|
|
len = length list;
|
|
first = head list;
|
|
pivot' = n: acc@{ left, right }: let el = elemAt list n; next = pivot' (n + 1); in
|
|
if n == len
|
|
then acc
|
|
else if strictLess first el
|
|
then next { inherit left; right = [ el ] ++ right; }
|
|
else
|
|
next { left = [ el ] ++ left; inherit right; };
|
|
pivot = pivot' 1 { left = []; right = []; };
|
|
in
|
|
if len < 2 then list
|
|
else (sort strictLess pivot.left) ++ [ first ] ++ (sort strictLess pivot.right));
|
|
|
|
/* Compare two lists element-by-element.
|
|
|
|
Example:
|
|
compareLists compare [] []
|
|
=> 0
|
|
compareLists compare [] [ "a" ]
|
|
=> -1
|
|
compareLists compare [ "a" ] []
|
|
=> 1
|
|
compareLists compare [ "a" "b" ] [ "a" "c" ]
|
|
=> 1
|
|
*/
|
|
compareLists = cmp: a: b:
|
|
if a == []
|
|
then if b == []
|
|
then 0
|
|
else -1
|
|
else if b == []
|
|
then 1
|
|
else let rel = cmp (head a) (head b); in
|
|
if rel == 0
|
|
then compareLists cmp (tail a) (tail b)
|
|
else rel;
|
|
|
|
/* Sort list using "Natural sorting".
|
|
Numeric portions of strings are sorted in numeric order.
|
|
|
|
Example:
|
|
naturalSort ["disk11" "disk8" "disk100" "disk9"]
|
|
=> ["disk8" "disk9" "disk11" "disk100"]
|
|
naturalSort ["10.46.133.149" "10.5.16.62" "10.54.16.25"]
|
|
=> ["10.5.16.62" "10.46.133.149" "10.54.16.25"]
|
|
naturalSort ["v0.2" "v0.15" "v0.0.9"]
|
|
=> [ "v0.0.9" "v0.2" "v0.15" ]
|
|
*/
|
|
naturalSort = lst:
|
|
let
|
|
vectorise = s: map (x: if isList x then toInt (head x) else x) (builtins.split "(0|[1-9][0-9]*)" s);
|
|
prepared = map (x: [ (vectorise x) x ]) lst; # remember vectorised version for O(n) regex splits
|
|
less = a: b: (compareLists compare (head a) (head b)) < 0;
|
|
in
|
|
map (x: elemAt x 1) (sort less prepared);
|
|
|
|
/* Return the first (at most) N elements of a list.
|
|
|
|
Type: take :: int -> [a] -> [a]
|
|
|
|
Example:
|
|
take 2 [ "a" "b" "c" "d" ]
|
|
=> [ "a" "b" ]
|
|
take 2 [ ]
|
|
=> [ ]
|
|
*/
|
|
take =
|
|
# Number of elements to take
|
|
count: sublist 0 count;
|
|
|
|
/* Remove the first (at most) N elements of a list.
|
|
|
|
Type: drop :: int -> [a] -> [a]
|
|
|
|
Example:
|
|
drop 2 [ "a" "b" "c" "d" ]
|
|
=> [ "c" "d" ]
|
|
drop 2 [ ]
|
|
=> [ ]
|
|
*/
|
|
drop =
|
|
# Number of elements to drop
|
|
count:
|
|
# Input list
|
|
list: sublist count (length list) list;
|
|
|
|
/* Return a list consisting of at most `count` elements of `list`,
|
|
starting at index `start`.
|
|
|
|
Type: sublist :: int -> int -> [a] -> [a]
|
|
|
|
Example:
|
|
sublist 1 3 [ "a" "b" "c" "d" "e" ]
|
|
=> [ "b" "c" "d" ]
|
|
sublist 1 3 [ ]
|
|
=> [ ]
|
|
*/
|
|
sublist =
|
|
# Index at which to start the sublist
|
|
start:
|
|
# Number of elements to take
|
|
count:
|
|
# Input list
|
|
list:
|
|
let len = length list; in
|
|
genList
|
|
(n: elemAt list (n + start))
|
|
(if start >= len then 0
|
|
else if start + count > len then len - start
|
|
else count);
|
|
|
|
/* Return the last element of a list.
|
|
|
|
This function throws an error if the list is empty.
|
|
|
|
Type: last :: [a] -> a
|
|
|
|
Example:
|
|
last [ 1 2 3 ]
|
|
=> 3
|
|
*/
|
|
last = list:
|
|
assert lib.assertMsg (list != []) "lists.last: list must not be empty!";
|
|
elemAt list (length list - 1);
|
|
|
|
/* Return all elements but the last.
|
|
|
|
This function throws an error if the list is empty.
|
|
|
|
Type: init :: [a] -> [a]
|
|
|
|
Example:
|
|
init [ 1 2 3 ]
|
|
=> [ 1 2 ]
|
|
*/
|
|
init = list:
|
|
assert lib.assertMsg (list != []) "lists.init: list must not be empty!";
|
|
take (length list - 1) list;
|
|
|
|
|
|
/* Return the image of the cross product of some lists by a function.
|
|
|
|
Example:
|
|
crossLists (x:y: "${toString x}${toString y}") [[1 2] [3 4]]
|
|
=> [ "13" "14" "23" "24" ]
|
|
*/
|
|
crossLists = builtins.trace
|
|
"lib.crossLists is deprecated, use lib.cartesianProductOfSets instead"
|
|
(f: foldl (fs: args: concatMap (f: map f args) fs) [f]);
|
|
|
|
|
|
/* Remove duplicate elements from the list. O(n^2) complexity.
|
|
|
|
Type: unique :: [a] -> [a]
|
|
|
|
Example:
|
|
unique [ 3 2 3 4 ]
|
|
=> [ 3 2 4 ]
|
|
*/
|
|
unique = foldl' (acc: e: if elem e acc then acc else acc ++ [ e ]) [];
|
|
|
|
/* Intersects list 'e' and another list. O(nm) complexity.
|
|
|
|
Example:
|
|
intersectLists [ 1 2 3 ] [ 6 3 2 ]
|
|
=> [ 3 2 ]
|
|
*/
|
|
intersectLists = e: filter (x: elem x e);
|
|
|
|
/* Subtracts list 'e' from another list. O(nm) complexity.
|
|
|
|
Example:
|
|
subtractLists [ 3 2 ] [ 1 2 3 4 5 3 ]
|
|
=> [ 1 4 5 ]
|
|
*/
|
|
subtractLists = e: filter (x: !(elem x e));
|
|
|
|
/* Test if two lists have no common element.
|
|
It should be slightly more efficient than (intersectLists a b == [])
|
|
*/
|
|
mutuallyExclusive = a: b:
|
|
(builtins.length a) == 0 ||
|
|
(!(builtins.elem (builtins.head a) b) &&
|
|
mutuallyExclusive (builtins.tail a) b);
|
|
|
|
}
|