Nando Lang

Nando Lang is a simple language and interpreter specification for educational purposes. I devised it on a piece of paper to help a web dev friend learn more about compiled languages and how programs written in higher-level languages actually run on a CPU.

The main points of this exercise are to show that:

1. The interpreter itself needs to be compiled to machine code; at the end of the day, something must be compiled to machine code, and that something is usually written in a compiled language like C, C++, Rust, Go, Odin, Zig, etc.

2. The code given to the interpreter does not need to be compiled. This mimics interpreted languages like JavaScript, Python, or Ruby. You can change the program code in the .nando files without needing to recompile!

Task

Write a C program that will act as a simple interpreter. Make it:

1. Accept an input file.

2. Parse each line in the file.

3. Parse space-separated values in each line.

4. Execute the parsed commands and print the variables at the end.

5. Support the following commands:

   • SET <var> <var|num>
   • ADD <var> <var|num>
   • SUB <var> <var|num>
   • MUL <var> <var|num>
   • DIV <var> <var|num>

6. Execute program1.nando and program2.nando properly:

   Program 1's non-zero results:

   r0 = 5.0
   r1 = 3.0
   

   Program 2's non-zero results:

   r2 = 1.0
   r3 = 1.0
   r4 = 12.0
   r5 = 16.0
   r6 = 8.0
   

<var> can be one of ten variables: r0 through r9.

<var|num> can be a variable or a floating-point value.

SET assigns a value to <var>.

ADD adds a value to <var>.

SUB subtracts a value from <var>.

MUL and DIV follow the same pattern, but for multiplication and division.

Build

To build with clang, do:

clang main.c -o nando-interpreter

(You can also use other compilers like GCC, MSVC, etc.)

This builds the interpreter as a binary/executable called nando-interpreter.

To run, do:

./nando-interpreter program1.nando
./nando-interpreter program2.nando

Unicode to UTF-8

See https://en.wikipedia.org/wiki/UTF-8#Description for how to convert code points to UTF-8 bytes.

See https://www.cogsci.ed.ac.uk/~richard/utf-8.cgi for a tool to convert unicode code points to UTF-8 bytes.

Alternatively, if you have the UTF-8 character, you can copy and paste it into a hex view of a file, and paste it as hex bytes to see the underlying representation.