run.dlang.io

This page describes a few features of run.dlang.io If you need help, please open an issue.

Keyboard shortcuts

Keyboard shortcut	Command
CTRL+Enter	run
CTRL+R	reset
CTRL+S	shorten (URL will be directly copied to the clipboard)
ALT+F	format

Examples

Example	Instructions
ASM	Assembly output
ASM	Try adding-inline
ASM	Try adding -O
AST	AST of DMD frontend (after semantic analysis)
IR	LDC only
JSON	JSON output from DMD
DDoc	DDoc output of DMD

Regression tester

It compares the output of all compiler from 2.060 to latest.

Example:

void main()
{
    import std.experimental.allocator; // so when was this added to Phobos?
}

https://run.dlang.io/is/3R4r1U

Tip: if you search for compiler errors, use -c -o- to speed up the run. You can learn more about dreg here.

Common flags

While most functionality is available via UI buttons, a few very infrequently used options aren't exposed. An additional benefit of adding the flag directly, is that - if a link is shared - it will be displayed immediately when the user hits on run. Thus, an incomplete of common LDC and DMD flags for which the Tour has added additional support.

Flag	Effect
-vcg-ast	Display the AST tree
-asm (DMD) / -output-s (LDC)	Show assembly
-c	Just compile
-Xf-	Show JSON output
-unittest	Run unttests
-D	Documentation build (HTML is shown)

Multiple files

run.dlang.io supports HAR which allows to use multiple files in a readable way:

• simple example
• using your own minimal object.d runtime

Using DPP

When a DPP file is detected, dpp will get called instead:

#include <stdio.h>
void main() {
    printf("Hello DPP.");
}

https://run.dlang.io/is/QnRbFt

Runnable DUB packages

run.dlang.io supports third-party libraries. A few examples:

mir

/+dub.sdl:
dependency "mir" version="~>1.1.1"
+/
import std.stdio;
import mir.combinatorics;
void main(string[] args)
{
    writeln([1, 2].combinations);
}

https://run.dlang.io/is/FIc6rd

mir-algorithm

/+dub.sdl:
dependency "mir-algorithm" version="~>0.6.14"
+/
import std.stdio;
void main(string[] args)
{
    import mir.ndslice.topology : iota;
    import mir.ndslice.algorithm : reduce;
    auto sl = iota(2, 3);
    size_t(0).reduce!"a + b"(sl).writeln;
}

https://run.dlang.io/is/3pNRH8

emsi_containers

/+dub.sdl:
dependency "emsi_containers" version="~>0.6.0"
+/
import std.stdio;
void main(string[] args)
{
    import containers;
    DynamicArray!int arr;
    arr ~= 1;
    foreach (e; arr)
        e.writeln;
}

https://run.dlang.io/is/AOBExl

libdparse

/+dub.sdl:
dependency "libdparse" version="~>0.7.2-alpha.5"
+/
import dparse.ast;
import std.stdio;

class TestVisitor : ASTVisitor
{
    alias visit = ASTVisitor.visit;

    override void visit(const FunctionDeclaration decl)
    {
		decl.name.text.writeln;
    }
}

void main()
{
    import dparse.lexer;
    import dparse.parser : parseModule;
    import dparse.rollback_allocator : RollbackAllocator;
    import std.array : array;
    import std.string : representation;

    auto sourceCode = q{
        void foo() @safe {}
    }.dup;
    LexerConfig config;
    auto cache = StringCache(StringCache.defaultBucketCount);
    auto tokens = getTokensForParser(sourceCode.representation, config, &cache);

    RollbackAllocator rba;
    auto m = parseModule(tokens.array, "test.d", &rba);
    auto visitor = new TestVisitor();
    visitor.visit(m);
}

https://run.dlang.io/is/kW7gQr

vibe-d

/+ dub.sdl:
dependency "vibe-d" version="~>0.8.2"
+/
import vibe.d;
import std.stdio;

void main()
{
    listenHTTP(":8080", (req, res) {
        res.writeBody("Hello, World: " ~ req.path);
    });
	runTask({
		scope (exit) exitEventLoop();
        auto req = requestHTTP("http://localhost:8080");
        req.bodyReader.readAllUTF8.writeln;
	});
    runApplication();
}

https://run.dlang.io/is/gI1NA5

Automem

/+dub.sdl:
dependency "automem" version="~>0.0.10"
+/
import std.stdio;
import automem;
import core.stdc.stdio;

void main() @nogc
{
    import std.experimental.allocator.mallocator : Mallocator;
    import std.algorithm : move;

    struct Point
    {
        int x;
        int y;
    }

    // the constructor can also take (size, init) or (size, range) values
    auto arr = UniqueArray!(Point, Mallocator)(3);

    const Point[3] expected1 = [Point(), Point(), Point()]; // because array literals aren't @nogc
    assert(arr[] == expected1);

    const Point[1] expected2 = [Point()];
    arr.length = 1;
    assert(*arr == expected2); //deferencing is the same as slicing all of it

    arr ~= UniqueArray!(Point, Mallocator)(1, Point(6, 7));
    const Point[2] expected3 = [Point(), Point(6, 7)];
    assert(arr[] == expected3);
    
    foreach (a; arr)
        printf("%d,%d\n", a.x, a.y);
}

https://run.dlang.io/is/hZE7IT

Miss your favorite library?

Add it here: https://github.com/dlang-tour/core-exec/blob/master/Dockerfile

With which parameter is dmd run?

DMD's new JSON output can sometimes be helpful. Simply compile with these parameters:

-Xi=compilerInfo -Xf=-

Example