Dialog

Dialog is a domain-specific language for creating works of interactive fiction. It is heavily inspired by Inform 7 (Graham Nelson et al. 2006) and Prolog (Alain Colmerauer et al. 1972).

An optimizing compiler, dialogc, translates high-level Dialog code into Z-code, a platform-independent runtime format originally created by Infocom in 1979.

Since Dialog version 0d/01 there's an interactive debugger, and since version 0g/01 there's a separate backend for the Å-machine story format.

The main discussion is happening in this forum thread.

Manual

The Dialog Manual will tell you everything.

Download

The release archive includes:

  • Full source code for the Dialog compiler.
  • Pre-built executable files for Linux (i386 and x86_64) and Windows.
  • The latest version of the Dialog standard library, and the standard debugging extension.
  • A copy of the manual.

The compiler is distributed under a 2-clause BSD license.

IFID Generator

For reasons outlined in the Treaty of Babel, the Dialog compiler may bug you about declaring a story-specific IFID. To generate the required declaration, simply click the button below.

Notable works

This is what Cloak of Darkness looks like in Dialog.

My IFComp 2018 game Tethered is the first published Dialog game.

Posted Thursday 22-Nov-2018 22:18

Discuss this page

Disclaimer: I am not responsible for what people (other than myself) write in the forums. Please report any abuse, such as insults, slander, spam and illegal material, and I will take appropriate actions. Don't feed the trolls.

Jag tar inget ansvar för det som skrivs i forumet, förutom mina egna inlägg. Vänligen rapportera alla inlägg som bryter mot reglerna, så ska jag se vad jag kan göra. Som regelbrott räknas till exempel förolämpningar, förtal, spam och olagligt material. Mata inte trålarna.

Anonymous
Tue 11-Dec-2018 18:44
if I have an object in a closed transparent container how do I override the default 'you can't reach obj' take fail message?

(instead of [take *]) doesn't seem to work in this case (scope?)
lft
Linus Åkesson
Wed 12-Dec-2018 10:35
if I have an object in a closed transparent container how do I override the default 'you can't reach obj' take fail message?

(instead of [take *]) doesn't seem to work in this case (scope?)

The "can't reach" message is printed by (refuse $), which is invoked before instead-of. So you can override refuse with a negated rule:

~(refuse [take *]) %% Don't refuse to take this object.
Anonymous
Thu 13-Dec-2018 12:55
Is it possible to suppress implicit actions temporarily.
For example
1.dropping something in a held container first tries to take the object before dropping.

2. putting something into something where the first something is in a held container tries to take before putting in

If I know that the take will always succeed can I suppress the first trying to take reporting.
lft
Linus Åkesson
Thu 13-Dec-2018 23:54
If I know that the take will always succeed can I suppress the first trying to take reporting.

Yes, there are several ways. You can override the before-predicate for that particular case, with a negative rule. For each particular action:

~(before [drop $X])
        ($X is #in $Y)
        ($Y is #heldby $Z)
        (current player $Z)

But many actions invoke a common predicate, '(ensure $ is held)', and you can add a new rule to that one instead:

(ensure $X is held)
        ($X is #in $Y)
        ($Y is #heldby $Z)
        (current player $Z)

When the given conditions are true, your rule will succeed, and this prevents the later rule definition in the library from executing.
Eleas
Björn Paulsen
Fri 14-Dec-2018 12:30
The Cloak of Darkness example seems bugged under 0.15. Attempting to go somewhere yields a crash:

fatal error: attempting to store to nonexistent local variable 3:
routine has 0 (pc = 0x2aba)
Eleas
Björn Paulsen
Fri 14-Dec-2018 12:34

Eleas wrote:

The Cloak of Darkness example seems bugged under 0.15. Attempting to go somewhere yields a crash:

fatal error: attempting to store to nonexistent local variable 3:
routine has 0 (pc = 0x2aba)

This is odd. I get the same error when running the first example in chapter 5. I'm running the win32 version of dialogc on Windows 10, in case that matters.
Eleas
Björn Paulsen
Fri 14-Dec-2018 12:44
I've now checked each release of the compiler, and found that moving between rooms only works under release 0b/01. Later than that leads to the fatal error described above.
Anonymous
Fri 14-Dec-2018 13:18

Eleas wrote:

I've now checked each release of the compiler, and found that moving between rooms only works under release 0b/01. Later than that leads to the fatal error described above.

Not sure if it's related but I only get the error when using Gargoyle. Frotz doesn't give the error. (latest versions Windows 10)
Eleas
Björn Paulsen
Fri 14-Dec-2018 13:54
Not sure if it's related but I only get the error when using Gargoyle. Frotz doesn't give the error. (latest versions Windows 10)

Thank you. Can verify. Does anyone know the best way to pass a bug report to one of the maintainers?
lft
Linus Åkesson
Fri 14-Dec-2018 14:47
This looks like a Dialog bug. Thanks for reporting; I'm on it!
lft
Linus Åkesson
Fri 14-Dec-2018 15:36
Fixed in 0c/04.
Anonymous
Tue 18-Dec-2018 13:05
Can I reference an object variable from within the scoring options?
(increase score by (#object variable))
lft
Linus Åkesson
Tue 18-Dec-2018 14:14
Can I reference an object variable from within the scoring options?
(increase score by (#object variable))

As a general rule, queries can't be nested; they don't even have return values.

(Confusingly, rule heads may contain nested expressions, but that is a special case of syntactic sugar.)

But output can be communicated using ordinary parameters. To take the output from one query, and use it as input in another, you would write the queries one after the other. Then you'd use a variable to carry the value.

Assuming you have a predicate ($ has score $) that assigns a score to every object:

        (#object has score $X) %% Here, $X becomes bound (i.e. to the output).
        (increase score by $X) %% Use the value of $X as input.
mstram
Sun 3-Feb-2019 08:01
The following code crashes the compiler

If I substitute the (else) with (if), I get a more reasonable message : "Error (if) without (then).

** The comment editor seems to strip away the indentation ... does it accept some kind of 'markup' ? (I.e. the second line (else) *was* indented.

Also I had much more in the source file, I isolated the crash down to these two lines.

Assertion failed!

Program: c:\bats\dialogc.exe
File: backend_z.c, Line 3348

Expression: call_lab

--------------------
(story title)
(else)
mstram
Sun 3-Feb-2019 08:15
The actual 'realistic' use case for the above was that I had accidentally "not-escaped" the title i.e.
(story title) ( Else) test file
instead of

(story title) \(Else \) test file
lft
Linus Åkesson
Sun 3-Feb-2019 08:54
Thanks! I'll fix that.

There's currently no tag to retain formatting in the comments; sorry for that. I've been using hardspaces to get around it. I suppose I'll fix that too.
mstram
Sun 3-Feb-2019 09:39
Are global flags (or maybe it's the (now) predicate) designed to work in "open code" (like global variables?

If I put :

(now)(a-global-flag) in "open code", I get :

"Special syntax cannot be redefined"

Mike
lft
Linus Åkesson
Sun 3-Feb-2019 21:54

mstram wrote:

Are global flags (or maybe it's the (now) predicate) designed to work in "open code" (like global variables?

If I put :

(now)(a-global-flag) in "open code", I get :

"Special syntax cannot be redefined"

Mike

Anything that starts in the very first column of a line is interpreted as a rule definition, so the compiler thinks you're trying to define a rule for a predicate called '(now)'. But that's special syntax, so its behaviour can't be modified.

If you would like the global flag to be initially set, define a rule with an empty rule body:

(a-global-flag)

This is analogous to how the initial values of other kinds of dynamic properties are defined. For instance:

(#box is #heldby #player)
(#box is open)
(current player #player)
mstram
Mon 4-Feb-2019 00:24
Ok, thanks, that works ... but ...

The "first-column-global" (fcg ? :)) is not showing up in the debugger's @dynamic output.

The flag *does* work though (of course),if I enter
(a-global-flag), giving the expected "Query succeeded:(a-global-flag)

The @dy(namic) cmd seems to be only finding global flags that are referenced inside a rule :

(test)
__ (now)(a-global-flag)


Mike
lft
Linus Åkesson
Mon 4-Feb-2019 15:02

mstram wrote:

The @dy(namic) cmd seems to be only finding global flags that are referenced inside a rule

That is correct. A predicate is only considered dynamic if it appears in a (now)-statement somewhere. So, if there's a (now) (a-global-flag) somewhere, then (a-global-flag) is regarded as a boolean variable that can be toggled at runtime. And its initial value is determined by the rule definitions for it. Otherwise, it behaves more like a boolean-valued function, and the rule definitions make up its function body.

It's a matter of terminology. Something that can change is dynamic, but something that cannot possibly change is not.
mstram
Wed 6-Feb-2019 11:12
This crashes both the windows and linux-64 compilers, version
0d02_0_19, and 0e01_0_20,but NOT the 0c05_0_17 version

#gnue
(name *) gnue
(dict *) plane
(vehicle *)


Again it's only a code fragment, but I was trying to split a larger program into multiple files.

Mike
lft
Linus Åkesson
Wed 6-Feb-2019 20:10
Thank you! I can reproduce it. Amusingly, I can get the program to compile by adding a room:

(room #x)

But it's still a compiler bug, of course, and I'll fix it as soon as possible.
lft
Linus Åkesson
Wed 13-Feb-2019 22:01
Fixed in 0e/02.
Anonymous
Sun 19-May-2019 12:00
I think there may be a bug with (fungibility enabled appearance $ $ $)

I noticed that when I had (fungibility enabled) an explicit (appearance $ $ $) rule set on an object did not fire until the object had been moved. After a bit of digging I came to the conclusion that the problem was with stdlib line 3788. What seems to be happening is that when nothing's been touched the list being handled by (fungibility-enabled appearance $ $ $) starts with an object with no appearance, which means that a rule fails on the first object and it never recurses.

If I add an (or) so that it reads

(if)($Ninc = 1)(then)
(appearance $Head $Rel $Loc)
(or)

it works. I'm not sure that adding an (or) simply to prevent failure is good style of course ...

Paul
lft
Linus Åkesson
Tue 21-May-2019 21:59
I think there may be a bug with (fungibility enabled appearance $ $ $)

Thank you! This was indeed a bug, and I've added the '(or)' in library version 0.24. I think it's a reasonably clean fix. The alternative would have been to add a default rule definition for '(appearance $ $ $)' with a blank rule body, but such a change would also have affected stories that do not make use of fungibility, so I decided against it. For now, at least.
Anonymous
Thu 6-Jun-2019 00:21
I can't seem to build this. backend.c and backend_z.h seem to be missing from the tarball.
lft
Linus Åkesson
Thu 6-Jun-2019 01:16
I can't seem to build this. backend.c and backend_z.h seem to be missing from the tarball.

Whoops! Should be fixed now in 0g/02, which is otherwise identical.
Anonymous
Sun 23-Jun-2019 18:52

lft wrote:

I can't seem to build this. backend.c and backend_z.h seem to be missing from the tarball.

Whoops! Should be fixed now in 0g/02, which is otherwise identical.


That got me going, thanks. Have you ever considered putting this in a public repository so that others can contribute, too?


I really like the idea of this system: it's a nice sweet spot between writing and programming.
Anonymous
Thu 15-Aug-2019 20:33
I have published a mostly-complete conversion of Pick Up the Phone Booth and Die to Dialog.

https://github.com/jpcompton/Dialog-diversions

Please enjoy dubious code examples, make improvements, or be inspired to greater heights!
Anonymous
Mon 16-Sep-2019 13:52
I just tried a hello world example and segfaulted the compiler (Dialog, release 0h/02, library 0.30, prebuilt for Linux x64)

$ cat test.dg
(story ifid) B0E2A7D1-45F7-46A1-8348-53ADA71F2CD8
(program entry point)
We'll find out how this works, slowly.

$ valgrind dialogc test.dg
==14539== Memcheck, a memory error detector
==14539== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==14539== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==14539== Command: dialogc test.dg
==14539==
==14539== Invalid read of size 1
==14539== at 0x12A4FA: addstr_escape.constprop.1 (in /usr/local/bin/dialogc)
==14539== by 0x12AE3D: emit_blorb (in /usr/local/bin/dialogc)
==14539== by 0x129FF1: backend_z (in /usr/local/bin/dialogc)
==14539== by 0x10D487: main (in /usr/local/bin/dialogc)
==14539== Address 0x0 is not stack'd, malloc'd or (recently) free'd
==14539==
==14539==
==14539== Process terminating with default action of signal 11 (SIGSEGV)
==14539== Access not within mapped region at address 0x0
==14539== at 0x12A4FA: addstr_escape.constprop.1 (in /usr/local/bin/dialogc)
==14539== by 0x12AE3D: emit_blorb (in /usr/local/bin/dialogc)
==14539== by 0x129FF1: backend_z (in /usr/local/bin/dialogc)
==14539== by 0x10D487: main (in /usr/local/bin/dialogc)
==14539== If you believe this happened as a result of a stack
==14539== overflow in your program's main thread (unlikely but
==14539== possible), you can try to increase the size of the
==14539== main thread stack using the --main-stacksize= flag.
==14539== The main thread stack size used in this run was 8388608.
==14539==
==14539== HEAP SUMMARY:
==14539== in use at exit: 613,930 bytes in 657 blocks
==14539== total heap usage: 1,170 allocs, 513 frees, 1,450,866 bytes allocated
==14539==
==14539== LEAK SUMMARY:
==14539== definitely lost: 7,600 bytes in 50 blocks
==14539== indirectly lost: 206,966 bytes in 102 blocks
==14539== possibly lost: 0 bytes in 0 blocks
==14539== still reachable: 399,364 bytes in 505 blocks
==14539== suppressed: 0 bytes in 0 blocks
==14539== Rerun with --leak-check=full to see details of leaked memory
==14539==
==14539== For counts of detected and suppressed errors, rerun with: -v
==14539== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)
Anonymous
Mon 16-Sep-2019 13:57
This seems to be linked to the (default) zblorb format. The others work fine.
lft
Linus Åkesson
Wed 18-Sep-2019 12:44
I just tried a hello world example and segfaulted the compiler (Dialog, release 0h/02, library 0.30, prebuilt for Linux x64)

Thanks for reporting it!

This appears to happen for small input (i.e. without the standard library), in combination with the zblorb format. I'll fix it tonight. Meanwhile, either switch to the z8 format or include the standard library.
lft
Linus Åkesson
Thu 19-Sep-2019 08:01
I just tried a hello world example and segfaulted the compiler (Dialog, release 0h/02, library 0.30, prebuilt for Linux x64)

This is now fixed in 0h/03.
Anonymous
Mon 23-Sep-2019 14:13
Using dialogc-0h03:

The following program crashes the compiler, regardless of the output format. It works on version 0d02.

(program entry point)
(now) ~($ has parent $)

Error messages:
backend_z.c:2010: generate_code: Assertion `ci->oper[0].value != DYN_HASPARENT' failed.
and
backend_aa.c:1350: compile_routines: Assertion `ci->oper[0].value != DYN_HASPARENT' failed.

--------------------------------------------------------

The following three programs crash the compiler when compiling for the Aa-machine but work fine on the Z-machine:

(program entry point)
(#a = $X)

Error message:
backend_aa.c:752: encode_dest: Assertion `0' failed.

--------------------------------------------------------

Note: I have been unable to minimize this program further because removing any line will cause the crash to disappear.

(program entry point)
($x = 3)
($y = 3)
($ = $)
([#a #b] = [#a #b])
([#a #b] = [#b #a])
([1 [@a] 3] = [1 [@a] 3])
([1 [@a #b] 3] = [2 [@a #b] 3])
([1 [@a #b] 3] = [1 [@a #b] 3])
([1 2 3 4] = [$a $b $c $d])

Error message:
backend_aa.c:3151: opersize: Assertion `aao.value <= 0x3f' failed.

--------------------------------------------------------

And a similar program, also as simplified as possible:

(program entry point)
($x = 3)
($y = 3)
($ = $)
([#a] = [])
([#a #b] = [#a #b])
([#a #b] = [#b #a])
([1 [#a #b] 3] = [1 [#a #b] 3])
([1 [#a #b] 3] = [2 [#a #b] 3])
([1 [#a #b] 3] = [1 [#a #b] 3])
([1 [#a #b] 3] = [1 [#a] 3])

Error message:
backend_aa.c:3151: opersize: Assertion `aao.value <= 0x3f' failed.
lft
Linus Åkesson
Mon 23-Sep-2019 23:36
Thanks! I'll look into these. The first two are corner cases that I hadn't thought of; they should be easy to fix.

The last two happen because the compiler is running out of registers for holding temporary values. Fixing this involves a more substantial implementation effort that I've been putting off. But it needs to be done, of course.
Anonymous
Sat 5-Oct-2019 02:31
Any chance of linking to the source repo, to accept patches. I've found a couple of nits in the documentation I could fix.
Anonymous
Fri 11-Oct-2019 03:39
Is there a GitHub project for this? I noticed a couple of tiny documentation bugs that I would submit a PR for.

Also, what's the trajectory here: do you know what "feature complete" looks like, and what's the journey there look like?

I've been dabbling in IF for quite some time; As a coder (I work in Clojure) I prefer the Dialog syntax over Inform (as nifty as Inform7 can be).

Also your forums are broken; database error, can't register.

HLS