Here we are going to show some code examples of small utility programs written using Rosella:
ls Clone
The Unix ls utility is used to show the contents of a directory. This example uses several pieces of Rosella. The FileSystem’s Directory type is used to read the directory contents. The Stream class from the Query library is used to iterate over all the directory contents and perform a variety of operations on each to produce the final formatted output.
This example currently acts like the command ”ls -a” by showing all items including hidden files and folders. It does not support other common arguments such as ”-l”.
1 class Rosella.FileSystem.Directory;
2 namespace Rosella.Query { extern function as_stream; }
3 namespace Rosella.String {extern function pad_end; }
4
5 function show_help(var args)
6 {
7 Rosella.IO.sayf("Usage: %s [directory]", args[0]);
8 exit(0);
9 }
10
11 function ls_main(var args)
12 {
13 var dirname = ".";
14 for(var i = 1; i < args; i++) {
15 var arg = args[i];
16 if(arg == "-h" || arg == "--help")
17 show_help(args);
18 else
19 dirname = arg;
20 }
21 var dir = new Rosella.FileSystem.Directory(dirname);
22 if(!dir.exists()) {
23 Rosella.IO.sayf("ls: cannot access %s: No such file or directory", dirname);
24 exit(-1);
25 }
26
27 Rosella.Query.as_stream(dir)
28 .map(function(e) { return e.short_name(); })
29 .sort()
30 .map(function(e) { return Rosella.String.pad_end(e, 20); })
31 .foreach(function(string e) { Rosella.IO.printf("%s\t", e); })
32 .tap(3, function() { say(""); })
33 .execute();
34
35 say("");
36 }
37
38 function main[main](var args)
39 {
40 var rosella = load_packfile("rosella/core.pbc");
41 var(Rosella.initialize_rosella)("filesystem", "query", "string");
42 ls_main(args);
43 }
nl Clone
The Unix nl utility is used to print the contents of a file with line numbers. The -a and -t options change the behavior to print some or all line numbers. This example uses the Rosella FileSystem library and the File class to get the file contents:
1 class Rosella.FileSystem.File;
2
3 function out(var output, var all) {
4 var i = 0;
5 for(string s in output) {
6 if(s != "" || all)
7 print(i++);
8 print(" ");
9 say(s);
10 }
11 }
12
13 function show_help(var args) {
14 print("Usage: ");
15 print(args[0]);
16 say(" [args] [file]");
17 say(" -a number all lines");
18 say(" -t number only nonempty lines");
19 say(" -h display this help message");
20 exit(0);
21 }
22
23 function main[main](var args) {
24 var rosella = load_packfile("rosella/core.pbc");
25 var(Rosella.initialize_rosella)("filesystem");
26 var filename = "";
27 var all;
28 for(var i = 1; i < args; i++) {
29 var arg = args[i];
30 if(arg == "-t")
31 all = false;
32 else if(arg == "-a")
33 all = true;
34 else if(arg == "-h" || arg == "--help")
35 show_help(args);
36 else
37 filename = arg;
38 }
39 if(filename == "") {
40 say("Please give a filename");
41 exit(0);
42 }
43 var file = new Rosella.FileSystem.File(filename);
44 if(!(file.exists())) {
45 print("nl: ");
46 print(filename);
47 say(": No such file or directory");
48 exit(-1);
49 }
50 string txt = file.read_all_text();
51 var output = split("\n", txt);
52 out(output, all);
53 }
Lucas Number Recursive function
#! winxed
function lucas_number(int num)
{
if (num == 0) return 2;
if (num == 1) return 1;
return lucas_number(num-1) + lucas_number(num-2);
}
function main()
{
var stdin = getstdin();
int num = stdin.readline();
int result = lucas_number(num);
say(result);
}Lucas Number Closed Formula
#! winxed
$loadlib "trans_ops";
function closed_formula(int num)
{
float result;
float golden_ratio = 1.618;
result = 1 - golden_ratio;
${ pow result, result, num };
${ pow golden_ratio, golden_ratio, num };
result = golden_ratio + result;
return result;
}
function roundUp(float num)
{
int result = num;
if (num >= (result + 0.5))
return (result + 1);
else
return result;
}
function main()
{
var stdin = getstdin();
int num = stdin.readline();
float result = closed_formula(num);
result = roundUp(result);
say(result);
}Generalized Fibonacci Sequence
#! winxed
function generate_Fibonacci_sequence(int r0, int r1)
{
var f = function (int num)
{
if (num == 0 ) return r0;
if (num == 1) return r1;
return f(num-1) + f(num-2);
};
return f;
}
function main()
{
var stdin = getstdin();
int r0 = stdin.readline();
int r1 = stdin.readline();
generate_Fibonacci_sequence(r0, r1);
}Gaussian Prime
#! winxed
$loadlib "trans_ops";
function is_gaussian_prime(int a, int b)
{
int power = 2;
a = pow(a, power);
b = pow(b, power);
int gaussian_number = a + b;
int result = is_normal_prime(gaussian_number);
if ( result == 1)
return 1;
else
return 0;
}
function pow(int a, int power)
{
float f_a = float(a);
float result;
${ pow result, f_a, power };
return int(result);
}
function is_normal_prime(int num)
{
for(int mod = 2; mod <= (num/2); mod++)
{
if (num % mod == 0)
return 0;
}
return 1;
}
function main()
{
var stdin = getstdin();
int a = stdin.readline();
int b = stdin.readline();
int result = is_gaussian_prime(a, b);
if (result == 1)
say(a, " + ", b, "*i is Gaussian Prime");
else
say(a, " + ", b, "*i is not Gaussian Prime");
}String inside other string
#! winxed
function check_for_searcher_string(string container, string searcher)
{
int checker = 0;
int counter = length(container);
int search_count = length(searcher);
string container_char;
string search_char;
say(counter);
say(search_count);
for (int index = 0; index < counter; index++)
{
if (checker != search_count && checker != (search_count-1))
{
container_char = substr(container, index, 1);
search_char = substr(searcher, checker ,1);
if (search_char == container_char)
checker++;
else
{
if (checker != 0)
{
checker++;
search_char = substr(searcher, checker ,1);
if (search_char != container_char)
checker = checker - 2;
}
}
}
}
if ((checker == search_count) || (checker == search_count-1))
return 1;
else
return 0;
}
function main()
{
var stdin = getstdin();
say("Enter Container String");
string container_string = stdin.readline();
say("Enter Searcher String");
string searcher_string = stdin.readline();
int result = check_for_searcher_string(container_string, searcher_string);
if (result == 1)
say("Searcher String is contained within Container String");
else
say("Searcher String is not contained within Container String");
}