Over the last couple of weeks I’ve been building my own parser, interpreter and compiler for Small Basic, a dialect of BASIC with only 14 keywords aimed at beginners. Despite, or perhaps because of, Small Basic’s simplicity some really fun programs have been developed, from games like Tetris and 3D Maze to a parser for the language itself. Small Basic provides primitive types for numbers, strings and associative arrays. There is no syntax provided for structures, but these can be easily modelled with the [...]

Microsoft Small Basic is a minimal implementation of the BASIC language aimed at beginners, with only 14 keywords. A few years back I used Small Basic as an early introduction to programming for my 2 young children (at the time 9 and 5). Small Basic’s library has a nice simple API for drawing shapes and moving a turtle around the screen which the kids loved. However I found the lack of function arguments and return values was quite limiting from a teaching perspective. After creating shapes we wanted to [...]

Small Basic, from Microsoft Dev Labs, is a minimal implementation of BASIC, employing only 14 keywords, aimed at beginners. In the last 2 articles I described building an internal DSL and parser to build an abstract syntax tree (AST) representation of the program with an interpreter for execution. In this article I’ll describe how to transform the AST to executable .Net IL code, thus building a compiler. Small Basic is an imperative programming language where programs are built up of procedures containing[...]

Microsoft Small Basic is a minimal implementation of the BASIC programming language aimed at beginners. In my last article I described the implementation of an interpreter for Small Basic using an internal DSL to specify the abstract syntax tree (AST) for programs. With the AST for the language well defined, a text parser for Small Basic programs is now relatively easy. There are quite a few options for writing parsers in F# from FsxLex and FSYyacc to hand rolled recursive descent parsers and parser combi[...]

Microsoft’s Small Basic is a minimal implementation of the BASIC programming language using only 14 keywords. It’s aimed at beginners with a very simple development environment and library. My kids have enjoyed playing with it particularly the Turtle API which are reminiscent of Logo. Small Basic programs can be run locally, online via Silverlight or migrated to full fat Visual Basic .Net. I’m quite interested in building Domain Specific Languages (DSLs), including embedded DSLs, parsers and compilers. Fo[...]