concatenation - SML, Write a function that concatenates a list of lists -


i need write concat function in standardml such that:

concat [[5,4,3],[],[9,5],[],[],[1,1]] = [5,4,3,9,5,1,1]

i new @ sml, don't think understand how breakdown lists , append them. answer may use built in append function

alist @ blist

thanks!

if you're expected write such function, i'm assuming have learned how build recursive functions iterate through list. knowledge plus @ function should enough.

if you're unsure list method use, lista @ listb creates new list combination of lista , listb, while item1 :: lista creates new list item1 added head of lista.


Comments

Post a Comment

Popular posts from this blog

php - Add the correct number of days for each month -

using following function can display years , months between 2 dates, how can add correct days each month array within each month? can't add days manually need account leap years etc. function yearmonth($start_date, $end_date) { $begin = new datetime( $start_date ); $end = new datetime( $end_date); $interval = new dateinterval('p1m'); // 1 month interval $period = new dateperiod($begin, $interval, $end); foreach ( $period $dt ) $years[$dt->format( "y" )][] = $dt->format( "f" ); return $years; } $list = yearmonth("2007-03-24", "2009-06-26"); var_dump($list); since nobody else answered: function yearmonth($start_date, $end_date) { $begin = new datetime( $start_date ); $end = new datetime( $end_date); $interval = new dateinterval('p1d'); // 1 month interval $period = new dateperiod($begin, $interval, $end); $lastmonth = null; $lastyear = null; $aresult = array(); forea...
Read more

java.util.scanner - How to read and add only numbers to array from a text file -

i'm learning java , have question regarding reading file want read numbers file contains strings well. here example of file: 66.56 "3 java 3-43 5-42 2.1 1 and here coding: public class test { public static void main (string [] args){ if (0 < args.length) { file x = new file(args[0]); try{ scanner in = new scanner( new fileinputstream(x)); arraylist<double> test = new arraylist<>(); while(in.hasnext()){ if(in.hasnextdouble()){ double f=in.nextdouble(); test.add(f);} else {in.next();} } catch(ioexception e) { system.err.println("exception during reading: " + e); } } my problem add 66.56,2.1 , 1 doesn't add 3 after "3 or ignores 3-43 , 5-42 can tell me how skip strings , add doubles here? thanks all said 3 ie; "3, 3-43 , 4-42 strings either u read string , split , check number @ " , - or put in space between characters , integers. jvm after compilation tre...
Read more