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The AIML pattern syntax is a very simple pattern language, substantially less complex than regular expressions and as such less than level 3 in the Chomsky hierarchy. To compensate for the simple pattern matching capabilities, AIML interpreters can provide preprocessing functions to expand abbreviations, remove misspellings, etc.
Tree patterns are used in some programming languages as a general tool to process data based on its structure, e.g. C#, [1] F#, [2] Haskell, [3] ML, Python, [4] Ruby, [5] Rust, [6] Scala, [7] Swift [8] and the symbolic mathematics language Mathematica have special syntax for expressing tree patterns and a language construct for conditional ...
In addition to a guard attached to a pattern, pattern guard can refer to the use of pattern matching in the context of a guard. In effect, a match of the pattern is taken to mean pass. This meaning was introduced in a proposal for Haskell by Simon Peyton Jones titled A new view of guards in April 1997 and was used in the implementation of the ...
The two lines are the two definitions of the function for the two kinds of arguments possible in this case – one where the list is empty (just return an empty list) and the other case where the list is not empty. Pattern matching is not strictly speaking always a choice construct, because it is possible in Haskell to write only one ...
A string-searching algorithm, sometimes called string-matching algorithm, is an algorithm that searches a body of text for portions that match by pattern. A basic example of string searching is when the pattern and the searched text are arrays of elements of an alphabet ( finite set ) Σ.
Generalizations of the same idea can be used to find more than one match of a single pattern, or to find matches for more than one pattern. To find a single match of a single pattern, the expected time of the algorithm is linear in the combined length of the pattern and text, although its worst-case time complexity is the product of the two ...
If the compressed file uses a variable width encoding it could be present a problem: for example, let “100” be the codeword for a and let “110100” be the codeword for b. If we are looking for an occurrence of a in the text we could obtain as result also an occurrence that is within the codeword of b : we call this event false match .
The syntax-case system can express the syntax-rules pattern language as a derived macro. The term macro system can be ambiguous because, in the context of Scheme, it can refer to both a pattern-matching construct (e.g., syntax-rules) and a framework for representing and manipulating syntax (e.g., syntax-case, syntactic closures).