REFAL – Recursive Functional Algorithmic Language [1], is a functional programming language, focused on symbolic calculations, processing and transformation of texts. This language has many dialects, for instance –
Note. There is no established way of writing the name of the REFAL language, there is a record both in Cyrillic and in Latin, entirely in the uppercase, with a capital letter or with a small one. In this document, when it comes to the family of languages, I will use the record in the uppercase (REFAL). However, when it comes to a specific dialect, I will use the record, which corresponds with the manual of a specific language. If the word “refal”; is used as an adjective, it will be written with a small letter, e.g. refal-expression, refal-program.
This implementation provides two similar dialects: Refal-5λ and Simple Refal. When referring to them, it is highly recommended to use the following record: Each word should start with a capital letter; the letter “lambda” should be Greek. In English, these names are usually recorded as Refal-5λ, Simple Refal. If the typographical capabilities do not allow the use of the “λ” symbol, it is recommended to use the Рефал-5-лямбда, or Refal-5-lambda.
Hereinafter, the suffix “λ-5” will often be omitted. Instead of “Refal-5λ”, it will be indicated by “Refal”
Initially, Simple Refal language was a research project and was developed by Alexander Konovalov aka Mazdaywik [pronounced as Mazdaischik]. The author wanted to understand how the REFAL code is compiled in the imperative code. The goal was to write a minimal but algorithmically complete compiler dialect of Basic REFAL. The simplicity of the translation program (e.g. single pass) was more important than the convenience of programming in the language. Despite this limitation (or, perhaps, due to it) the language turned out to be quite coherent and consistent.
The compiler was simple enough, so it has been used as a testing ground for several course papers and final qualification papers of the bachelor at Bauman Moscow State Technical University in the IU9 “Computer science and technologies” department.
The abilities investigated through the compiler are the following:
During its development, the compiler departed slightly from its original simplicity. First of all, it was used as a back-end for Module Refal, so there were added the following features: identifiers, abstract data types and static boxes. Then we used the compiler for implementation of nested functions research. As a result, the language gained a new convenient tool.
Gradually, the author (Mazdaywik) realized that it was very inconvenient to program in the language because of the predeclarations necessity. Moreover, there was no use in a separate incompatible dialect. Considering that the language was very close to the classical REFAL-5 dialect, it was decided to convert it into a REFAL-5 dialect compiler, which would have the main features of the Simple Refal (higher-order functions and nested functions). This dialect was called Refal-5λ.
Translation to English of this paper is prepared by Philip Cadena filcadena@gmail.com at 2018-01-18
Markdown is prepared by Liudmila Markova luckymarkin@gmail.com at 2018-01-18