Programming a fully functional Eliza Robot is not easy, but it should not be too hard to produce a nice ``doll'' once you (a) grasped the way Ken's Bot work, (b) you learned how to write simple regular expressions and (c) you played around with some Eliza Bots or read some texts about them.
This is a slightly edited version from 'help bot'.
To see what words your bot already responds to type
To teach your bot to respond to 'donut' with either 'I like donuts too.' or
'Donuts are very tasty!' just type '@addword botname' and enter the keyword
'donut'. Then enter the appropriate responses a line at a time. End with
a single period on a line by itself.
Don't try to build a large list of simple word matching patterns, but rather study how to work with patterns
Suppose you wished your bot to hear something like
MY DONUT ISN'T VERY TASTY
and respond with
WHAT'S SO GREAT ABOUT A TASTY DONUT?
To do this you must teach your bot to respond to the pattern
MY a ISN'T VERY b.
To understand what patterns look like, type
'seepat botname' and study the
examples. For additional assistance on understanding the syntax of patterns
see the next section 6.3.1.
When you think you are ready to add a pattern type
@addpat botname' and enter the following line when asked to do so:
my %(%w*%) isn't very %(.*%)
Then type in the response form:
What's so great about a %2 %1?
Add as many response forms as you wish on separate lines. End with a
period on a single line.
These responses are triggered whenever your bot can't find a keyword, a
pattern, or a question. To see the responses already programmed type:
To add a new random response type:
'addrandom botname' and enter a new response.
When your bot senses a question is being asked it responds with a random
'answer'. To see the random question responses already programmed into
your bot type
'seequestionresponses botname'. To add a new response
'mvpat 7 on botname'. You will then be asked to enter a line number to move pattern to.
Caution: This bot was designed for serious educational and experimental purposes. It makes an excellent 'guide' or 'tutor' and is an interesting vehicle for the study of the limits of language understanding using an 'Eliza' approach. BUT.. it has great spam potential since it responds to nearly everything it hears. 'Hush botname' when not needed and please be considerate of others around you ..
Finally, as always ``
@examine <bot>'' to see the full list
of verbs !
Ken's Turing Bot works with regular expressions as mentionned above. It is probably best to learn by example and then try out more complex patterns by learning how to use regular expressions.
Regular expressions are similar in most programming languages and fancy editors:
So, building a nice Turing bot is a good exercise for learning regexps which come very handy when you write Perl scripts or if you want to do fancy text processing with an editor. Here is the complete syntax for regular expressions:
Regular expression matching allows you to test whether a string fits into a specific syntactic shape. You can also search a string for a substring that fits a pattern. See also the built-in function match()/rmatch().
A regular expression describes a set of strings. The simplest case is
one that describes a particular string; for example, the string
`foo' when regarded as a regular expression matches
`foo' and nothing else. Nontrivial regular expressions use
certain special constructs so that they can match more than one
string. For example, the regular expression
either the string
`foo' or the string
`bar'; the regular
`c[ad]*r' matches any of the strings
`cadddar' and all
other such strings with any number of
Regular expressions have a syntax in which a few characters are
special constructs and the rest are "ordinary". An ordinary character
is a simple regular expression that matches that character and nothing
else. The special characters are
`%'. Any other character appearing in a regular expression is
ordinary, unless a
`%' precedes it.
`f' is not a special character, so it is ordinary,
`f' is a regular expression that matches the
`f' and no other string. (It does *not*, for example,
match the string
`o' is a regular
expression that matches only
Any two regular expressions A and B can be concatenated. The result is a regular expression which matches a string if A matches some amount of the beginning of that string and B matches the rest of the string.
As a simple example, we can concatenate the regular expressions
`o' to get the regular expression
which matches only the string
`fo'. Still trivial.
The following are the characters and character sequences that have special meaning within regular expressions. Any character not mentioned here is not special; it stands for exactly itself for the purposes of searching and matching.
`a.b', which matches any three-character string that begins with
`a'and ends with
`*'applies to the
`f'followed by any number of
The case of zero
`o''s is allowed:
`fo*' does match
`*' always applies to the *smallest* possible preceding
`fo*' has a repeating
`o', not a
The matcher processes a
`*' construct by matching,
immediately, as many repetitions as can be found. Then it continues
with the rest of the pattern. If that fails, it backtracks,
discarding some of the matches of the
`*''d construct in
case that makes it possible to match the rest of the pattern. For
`c[ad]*ar' against the string
`[ad]*' first matches
but this does not allow the next
`a' in the pattern to match.
So the last of the matches of
`[ad]' is undone and the
`a' is tried again. Now it succeeds.
Let's have a look at an example from Ken's Bot:
.* will match any chain of characters. E.g. this pattern would
match something like:
it's time now
but it would not match something like:
I tell you it's time now
a pattern like this would:
.* it's .*
See below for what the
%(.. %) expression does in addition.
`*'except that at least one match for the preceding pattern is required for
`c[ad]r'+ does not match
`cr'but does match anything else that
`*'except that it allows either zero or one match for the preceding pattern. Thus,
`cdr', and nothing else.
`['begins a "character set", which is terminated by a
`]'. In the simplest case, the characters between the two brackets form the set. Thus,
`[ad]*'matches any string of
`d''s (including the empty string), from which it follows that
Character ranges can also be included in a character set, by writing
two characters with a
`-' between them. Thus,
matches any lower-case letter. Ranges may be intermixed freely with
individual characters, as in
`[a-z$%.]', which matches any lower case letter or
`%' or period.
Note that the usual special characters are not special any more inside
a character set. A completely different set of special characters
exists inside character sets:
To include a
`]' in a character set, you must make it the first
character. For example,
`a'. To include a
`-', you must use it in a context
where it cannot possibly indicate a range: that is, as the first
character, or immediately after a range.
[^ ... ]'
`[^'begins a "complement character set", which matches any character except the ones specified. Thus,
`[^a-z0-9A-Z]'matches all characters *except* letters and digits.
`^' is not special in a character set unless it is the first
character. The character following the
`^' is treated as if
it were first (it may be a
`-' or a
`^' is a special character that matches the empty string -
but only if at the beginning of the string being matched. Otherwise
it fails to match anything. Thus,
`^foo' matches a
`foo' which occurs at the beginning of the string.
`^'but matches only at the *end* of the string. Thus,
`xx*$'matches a string of one or more
`x''s at the end of the string.
`%'), and it introduces additional special constructs.
`%' quotes special characters,
`%$' is a
regular expression that
`%[' is a regular expression
that matches only
`[', and so on.
For the most part,
`%' followed by any character matches
only that character. However, there are several exceptions:
characters that, when
`%', are special constructs. Such characters
are always ordinary when encountered on their own.
No new special characters will ever be defined. All extensions to the
regular expression syntax are made by defining new two-character
constructs that begin with
`%|'in between form an expression that matches anything that either A or B will match.
`foo%|bar' matches either
`bar' but no other string.
`%|' applies to the largest possible surrounding
expressions. Only a
`%( ... %)' grouping can limit the grouping
Full backtracking capability exists for when multiple
`%|''s are used.
`\%( ... \%)'
1. To enclose a set of
`%|' alternatives for other
`%(foo%|bar%)x' matches either
2. To enclose a complicated expression for a following
to operate on. Thus,
`bananana', etc., with any number of
3. To mark a matched substring for future reference.
This last application is not a consequence of the idea of a
parenthetical grouping; it is a separate feature that happens to be
assigned as a second
meaning to the same
`%( ... %)' construct because there is
no conflict in practice between the two meanings. Here is an
explanation of this feature:
`%( ... %)'construct, the matcher remembers the beginning and end of the text matched by that construct. Then, later on in the regular expression, you can use
`%'followed by DIGIT to mean "match the same text matched by the DIGIT'+th
`%( ... %)'construct in the pattern." The
`%( ... %)'constructs are numbered in the order that their
`%(''s appear in the pattern.
The strings matching the first nine
`%( ... %)' constructs
appearing in a regular expression are assigned numbers 1 through 9 in
order of their
`%9' may be used to refer
to the text matched by
`%( ... %)' construct.
`%(.*%)%1' matches any string that is
composed of two
identical halves. The
`%(.*%)' matches the first half,
which may be
anything, but the
`%1' that follows must match the same
Let's look at an example from Ken's Bot:
1 your %(.*%)
my %1? Why do you wish to know?
I would rather not discuss my '%1' if it's allright with you...
Tell me yours first!
7 %(%w*%) is %(.*%)
Suppose %1 were not %2? What then?
What is so %2 about %1?
%1? how so?
The first element in each pattern is matched against the input and
the other elements are possible replies using the matched pattern.
`%bfoo%b'matches any occurrence of
`foo'as a separate word.
`balls'as a separate word.
For the purposes of this construct and the five that follow, a word is defined to be a sequence of letters and/or digits.
You can look at a short text in french that summarizes regular expressions.
A note about regexps in emacs and perl. Please remember that the ``
is replaced by the ``
Replacing complex patterns in emacs is a good way to learn regular expressions.
Take a random text and start playing around. Example:
would replace a pattern like this:
ctrl_ will undo changes so you can retry and also
Meta-N will allow to edit previous
arguments in the
M-x query-replace-regexp dialog.