Mœbius: metaprogramming using contextual types: the stage where system f can pattern match on itself

We describe the foundation of the metaprogramming language, Mœbius, which supports the generation of polymorphic code and, more importantly, the analysis of polymorphic code via pattern matching. Mœbius has two main ingredients: 1) we exploit contextual modal types to describe open code together with the context in which it is meaningful. In Mœbius, open code can depend on type and term variables (level 0) whose values are supplied at a later stage, as well as code variables (level 1) that stand for code templates supplied at a later stage. This leads to a multi-level modal lambda-calculus that supports System-F style polymorphism and forms the basis for polymorphic code generation. 2) we extend the multi-level modal lambda-calculus to support pattern matching on code. As pattern matching on polymorphic code may refine polymorphic type variables, we extend our type-theoretic foundation to generate and track typing constraints that arise. We also give an operational semantics and prove type preservation. Our multi-level modal foundation for Mœbius provides the appropriate abstractions for both generating and pattern matching on open code without committing to a concrete representation of variable binding and contexts. Hence, our work is a step towards building a general type-theoretic foundation for multi-staged metaprogramming that, on the one hand, enforces strong type guarantees and, on the other hand, makes it easy to generate and manipulate code. This will allow us to exploit the full potential of metaprogramming without sacrificing the reliability of and trust in the code we are producing and running.

The Identity Construction Through Music Notation of The Indigenous Style of Gitar Tunggal Lampung Pesisir

This study aims to reveal the meaning of music notation writing of gitar tunggal Lampung Pesisir written by Imam Rozali. Imam is a gitar tunggal player who wrote his technique and playing style in notation symbols. This article uses a case study research design with pattern matching techniques (Yin, 2018). Data were collected through observation, interviews, document analysis, and audio recordings. A series of tests were carried out on the notation and other supporting information to improve the validity of the data. Laboratory analysis was carried out to describe signs, interpret symbols, and compare Western musical notation. As a result, (1) the music notation written by Imam Rozali is a musical expression used as a medium for remembering; (2) the writing of Imam Rozali’s musical notation constructs his musical identity as a Gitar tunggal Lampung Pesisir player; (3) Imam Rozali’s music notation symbolizes an indigenous style which has its concept of gitar tunggal music; (4) Imam Rozali tries to add value to his musical identity among gitar tunggal players because the notation is a symbol of intellectuality.

Functional Encryption for Pattern Matching with a Hidden String

We propose a new functional encryption for pattern matching scheme with a hidden string. In functional encryption for pattern matching (FEPM), access to a message is controlled by its description and a private key that is used to evaluate the description for decryption. In particular, the description with which the ciphertext is associated is an arbitrary string w and the ciphertext can only be decrypted if its description matches the predicate of a private key which is also a string. Therefore, it provides fine-grained access control through pattern matching alone. Unlike related schemes in the literature, our scheme hides the description that the ciphertext is associated with. In many practical scenarios, the description of the ciphertext cannot be public information as an attacker may abuse the message description to identify the data owner or classify the target ciphertext before decrypting it. Moreover, some data owners may not agree to reveal any ciphertext information since it simply gives greater advantage to the adversary. In this paper, we introduce the first FEPM scheme with a hidden string, such that the adversary cannot get any information about the ciphertext from its description. The security of our scheme is formally analyzed. The proposed scheme provides both confidentiality and anonymity while maintaining its expressiveness. We prove these security properties under the interactive general Diffie–Hellman assumption (i-GDH) and a static assumption introduced in this paper.

Eye of Devil: Face Recognition in Real World Surveillance Video with Feature Extraction and Pattern Matching

People lost, people missing etc., these are the words we come across whenever there is any mass gathering events going on or in crowded areas. To solve this issue some traditional approaches like announcements are in use. One idea is to identify the person using face recognition and pattern matching techniques. There are several techniques to implement face recognition like extraction of facial features by using the position of eyes, nose, jawbone or skin texture analysis etc., By using these techniques a unique dataset can be created for each human. Here the photograph of the missing person can be used to extract these facial features. After getting the dataset of that individual, by using pattern matching techniques, there is a scope to find the person with same facial features in the crowd images or videos. Keywords: Face-Recognition, Image-Processing, Feature extraction, Video-Processing, Pattern-Matching.