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0 Zzrk - Adventures in the Great Unsaturated Grammar
1 ====
2
3 What is it?
4 -----------
5
6 Zzrk is a toy text adventure (or, if you prefer, a toy work of interactive
7 fiction) written in "pure" Zz -- assuming such a concept makes any sense.
8 Zz is a dynamic meta-language designed for the APE parallel computing
9 project to enable variants on languages such as FORTRAN to be quickly
10 developed. As such, Zz maintains very little distinction between the
11 language definition level and the language use level. For this reason, it
12 might be more accurate to describe Zz as a self-modifying grammar.
13
14 Since Zz is typically used to define programming languages, I thought it
15 would be a nice abuse to try to use it to write an actual program (albeit
16 a very language-like one.) The result is Zzrk.
17
18
19 Playing the Game
20 ----------------
21
22 First, you need an implementation of Zz. The only one I've found, and
23 subsequently the one I've written Zzrk around, is OpenZz. It can be
24 gotten from http://openzz.sourceforge.net/.
25
26 Although OpenZz does have an interactive mode, it unfortunately assumes
27 you're using Zz to describe a compiler. Since I assume you'll want to
28 play Zzrk interactively (as opposed to typing the sequence of actions you
29 want to take into a text file, piping it through Zzrk, and seeing what
30 happens), here's a guide to working around some of OpenZz's drawbacks.
31
32 First, you can't just specify zzrk.zz as the input to ozz. Instead,
33 start OpenZz, then at the "ozz>" prompt, type
34
35 /include "zzrk.zz"
36
37 You can then treat the "ozz>" prompt as the prompt for the adventure
38 game parser. Try the usual actions, and see what happens. Be forewarned
39 that any unrecognizable command on your part -- an unknown verb, noun, or
40 other part of speech -- will trigger a syntax error. And, because OpenZz
41 thinks you are the input to a compiler, accumulating 10 of these errors
42 will actually cause OpenZz to quit!
43
44
45 The Game Itself
46 ---------------
47
48 The game itself is embarrassingly simplistic, but there are a few nominal
49 puzzles just to demonstrate that the standard adventure game furniture can
50 be concocted in Zz. Collecting treasures will get you points, and
51 obtaining 50 points will win the game (that is, if you have 50 points and
52 you type "score", you will get a message telling you that you have won.
53 You will still need to quit OpenZz through some other manual action, such
54 as typing Ctrl-D, or causing syntax errors.)
55
56
57 Comments
58 --------
59
60 I originally wrote zzrk.zz on November 21st, 2003. I gave it actual
61 puzzles, wrote this readme, and released it under a BSD license on
62 May 6, 2007.
63
64 A couple of annoying things about Zz...
65
66 The documentation for OpenZz doesn't mention that the /if { } construct
67 has a variant that takes an else clause. And, /return does not actually
68 cause an immediate return, it only assigns a value to the nonterminal
69 under consideration. For these reasons, I was originally writing many of
70 my tests twice (like /if a == b {} /if a != b {}). Then I noticed, in
71 examining the results of /krules, that the kernel does in fact support
72 else. The fact that curly braces actually denote lists means they're not
73 optional in tests though, and the nesting is still pretty annoying.
74
75 The other annoying thing is that there's no way to prioritize selection
76 of nonterminals. For example, I feel very strongly that it ought to be
77 possible to write the score_of production like this:
78
79 /$num_t -> "score_of" coin { /return 5 }
80 /$num_t -> "score_of" jewel { /return 10 }
81 /$num_t -> "score_of" sceptre { /return 15 }
82 /$num_t -> "score_of" crown { /return 20 }
83 /$num_t -> "score_of" object^$ { /return 0 }
84
85 On the basis that coin et al. are more specific than object^$, and should
86 be selected before it. But, it's not possible to set this up, at least as
87 far as I can see. Which is a pity, because this sort of "catch-all"
88 mechanism would also enable much better error handling.
89
90 A couple of nice things about Zz...
91
92 The parser-oriented approach is, of course, very nice for an adventure
93 game. It was very simple to create a parser which is in some respects
94 sophisticated: it can understand "pick up the key" just as easily as
95 "get key". Even nicer is that the scope rules (verbs that apply only
96 to objects that are being held, are in the same room, or either) are
97 implemented directly as productions in the grammar.
98
99 Changing the grammar of the language you are using *on the fly* can be
100 very scary, but also very powerful. Note that until you learn what the
101 magic word is, you can't even use it without causing a syntax error.
102 But afterward it is a full-fledged part of the parser's vocabulary.
103 Note also that this is how the properties of an object are updated:
104 the production which handles "e_exit square_room" is replaced by one
105 that returns a different value, once the door is open.
106
107 Some of the action productions are a bit clumsy because they contain
108 logic that should probably be associated with the object instead.
109 Putting lists of statements in a property of the object, and using
110 Zz's /execute facility, would probably allow a "method-like" style
111 that permits this, but I haven't played with it.
112
113 Lastly, it's interesting to note that internal helper functions (not
114 to mention the full complement of OpenZz builtins) are all available to
115 the player during the course of the game. For example, try
116
117 move player to chest
118
119 and see what happens. Even better, why not try
120
121 object snake "snake" "Eek!" wall wall wall wall "no" loc player
122 look
123 examine snake
124
125 Using Zz's notion of scopes, it might be possible to protect the
126 internals from being invoked like this, but considering Zzrk is just a
127 toy it hardly seems worth bothering.
128
129 Happy adventuring!
130
131 -Chris Pressey
132 May 6, 2007
133 Vancouver, BC
+0
-134
readme.txt less more
0 Zzrk - Adventures in the Great Unsaturated Grammar
1 ====
2
3 What is it?
4 -----------
5
6 Zzrk is a toy text adventure (or, if you prefer, a toy work of interactive
7 fiction) written in "pure" Zz -- assuming such a concept makes any sense.
8 Zz is a dynamic meta-language designed for the APE parallel computing
9 project to enable variants on languages such as FORTRAN to be quickly
10 developed. As such, Zz maintains very little distinction between the
11 language definition level and the language use level. For this reason, it
12 might be more accurate to describe Zz as a self-modifying grammar.
13
14 Since Zz is typically used to define programming languages, I thought it
15 would be a nice abuse to try to use it to write an actual program (albeit
16 a very language-like one.) The result is Zzrk.
17
18
19 Playing the Game
20 ----------------
21
22 First, you need an implementation of Zz. The only one I've found, and
23 subsequently the one I've written Zzrk around, is OpenZz. It can be
24 gotten from http://openzz.sourceforge.net/.
25
26 Although OpenZz does have an interactive mode, it unfortunately assumes
27 you're using Zz to describe a compiler. Since I assume you'll want to
28 play Zzrk interactively (as opposed to typing the sequence of actions you
29 want to take into a text file, piping it through Zzrk, and seeing what
30 happens), here's a guide to working around some of OpenZz's drawbacks.
31
32 First, you can't just specify zzrk.zz as the input to ozz. Instead,
33 start OpenZz, then at the "ozz>" prompt, type
34
35 /include "zzrk.zz"
36
37 You can then treat the "ozz>" prompt as the prompt for the adventure
38 game parser. Try the usual actions, and see what happens. Be forewarned
39 that any unrecognizable command on your part -- an unknown verb, noun, or
40 other part of speech -- will trigger a syntax error. And, because OpenZz
41 thinks you are the input to a compiler, accumulating 10 of these errors
42 will actually cause OpenZz to quit!
43
44
45 The Game Itself
46 ---------------
47
48 The game itself is embarrassingly simplistic, but there are a few nominal
49 puzzles just to demonstrate that the standard adventure game furniture can
50 be concocted in Zz. Collecting treasures will get you points, and
51 obtaining 50 points will win the game (that is, if you have 50 points and
52 you type "score", you will get a message telling you that you have won.
53 You will still need to quit OpenZz through some other manual action, such
54 as typing Ctrl-D, or causing syntax errors.)
55
56
57 Comments
58 --------
59
60 I originally wrote zzrk.zz on November 21st, 2003. I gave it actual
61 puzzles, wrote this readme, and released it under a BSD license on
62 May 6, 2007.
63
64 A couple of annoying things about Zz...
65
66 The documentation for OpenZz doesn't mention that the /if { } construct
67 has a variant that takes an else clause. And, /return does not actually
68 cause an immediate return, it only assigns a value to the nonterminal
69 under consideration. For these reasons, I was originally writing many of
70 my tests twice (like /if a == b {} /if a != b {}). Then I noticed, in
71 examining the results of /krules, that the kernel does in fact support
72 else. The fact that curly braces actually denote lists means they're not
73 optional in tests though, and the nesting is still pretty annoying.
74
75 The other annoying thing is that there's no way to prioritize selection
76 of nonterminals. For example, I feel very strongly that it ought to be
77 possible to write the score_of production like this:
78
79 /$num_t -> "score_of" coin { /return 5 }
80 /$num_t -> "score_of" jewel { /return 10 }
81 /$num_t -> "score_of" sceptre { /return 15 }
82 /$num_t -> "score_of" crown { /return 20 }
83 /$num_t -> "score_of" object^$ { /return 0 }
84
85 On the basis that coin et al. are more specific than object^$, and should
86 be selected before it. But, it's not possible to set this up, at least as
87 far as I can see. Which is a pity, because this sort of "catch-all"
88 mechanism would also enable much better error handling.
89
90 A couple of nice things about Zz...
91
92 The parser-oriented approach is, of course, very nice for an adventure
93 game. It was very simple to create a parser which is in some respects
94 sophisticated: it can understand "pick up the key" just as easily as
95 "get key". Even nicer is that the scope rules (verbs that apply only
96 to objects that are being held, are in the same room, or either) are
97 implemented directly as productions in the grammar.
98
99 Changing the grammar of the language you are using *on the fly* can be
100 very scary, but also very powerful. Note that until you learn what the
101 magic word is, you can't even use it without causing a syntax error.
102 But afterward it is a full-fledged part of the parser's vocabulary.
103 Note also that this is how the properties of an object are updated:
104 the production which handles "e_exit square_room" is replaced by one
105 that returns a different value, once the door is open.
106
107 Some of the action productions are a bit clumsy because they contain
108 logic that should probably be associated with the object instead.
109 Putting lists of statements in a property of the object, and using
110 Zz's /execute facility, would probably allow a "method-like" style
111 that permits this, but I haven't played with it.
112
113 Lastly, it's interesting to note that internal helper functions (not
114 to mention the full complement of OpenZz builtins) are all available to
115 the player during the course of the game. For example, try
116
117 move player to chest
118
119 and see what happens. Even better, why not try
120
121 object snake "snake" "Eek!" wall wall wall wall "no" loc player
122 look
123 examine snake
124
125 Using Zz's notion of scopes, it might be possible to protect the
126 internals from being invoked like this, but considering Zzrk is just a
127 toy it hardly seems worth bothering.
128
129 Happy adventuring!
130
131 -Chris Pressey
132 May 6, 2007
133 Vancouver, BC