langatator/README.md

# Langatator

A very basic interpreted imperative programming language.

## Background

The goal of this project is to create a simple implementation of a BASIC-like language just to learn a few things along the way and practice my C programming skills.

No need to do complex things, just to create a simple interpreted language that can be used to do some arithmetics and create for example a number guessing game.

I didn't really study how others languages works beforehand, I'm just guessing how I'm implementing things so that I can make mistakes to learn from.

## Progress

- 2022-04-29 Implementation of a basic evaluator engine to evaluate arithmetic expressions and call functions
- 2022-05-15 Clear progress being able to use simple while and if though thre are many glitches

ToDo List:

- [X] pow operator
- [X] binary operators
- [X] implement basic math functions
- [X] implement random_int(min, max)
- [X] implement print_number(message)
- [X] add unit tests
- [X] allow to set variables
- [X] read line comments
- [X] add modulus operator '%'
- [X] add input_number() std function
- [X] add NULL type (dirty way to handle no returns and some errors)
- [X] add type() std function and others type checking functions
- [X] add ceil() and floor() std functions
- [X] base of the CLI
- [X] read a file
- [X] if statements
- [X] while statements (with break and continue)

- [ ] add multiple characters operators
- [ ] add inclusive operators like '!=', '>=', '<='
- [ ] add functions support
- [ ] add priority operators
- [ ] add multiline expressions
- [ ] add short hand if without 'end'
- [ ] add repeat statement
- [ ] add static string support (just for ui)
- [ ] add print_string function
- [ ] add basic number list support
- [ ] add fully features strings support
- [ ] add function to access to environment variables

- [ ] add REPL environment
- [ ] evaluate expression from stdin
- [X] add config header file
- [X] ability to modify keywords and customize the lang
- [ ] add more config options

- [ ] add [classic problem solving](https://rosettacode.org) with code examples
- [ ] add Web Assembly support and publish a demo website

- [ ] refactor: use malloc for list
- [ ] refactor: remove inconsistency on how functions returns error codes

## Installation

You will need to compile the code from source.

- Clone this repository
- Then compile (eg. with `make`)

I use GNU Make with GCC, but I'm sure you can use any C compilers though you may need to edit some part of the code to cope with other compilers (eg. binary constants).

## Unit testing

I try to have some sort of code coverage, you can run the unit tests by issuing `make test`

## The language

You would be able to use the lang directly via CLI, via a REPL or by writing in a file (file ext `.ltor`).

One instruction set per line.

### Comments

Can only use single line comments with `#`

```
# this is a comment
```

### Data types

To begin with and order to simplify things we would only have numbers as datatypes.

When a variable is declared it can be 32 bit integer or 32 bit float.

The language may support strings literals in the future.

### Expression evaluation

function calls: func(arg_a, arg_b)
operators: +, *, /, ^, %, =, <, >, &, |, !

### Set a variable

```
set {VARNAME} to {EXPRESSION}
```

### Evaluate an expression without using the result

```
print_number(42)
```

### function definition

```
function {NAME} do
  ...
end
```

### Conditional structure

```
if {EXPRESSION} then
  ...
end
```

### Conditional loop

```
while {EXPRESSION} do
  ...
end
```

### Unconditional loop

```
repeat {INT EXPRESSION} do
  ...
end
```

```
repeat i from {INT EXPRESSION} to {INT EXPRESSION} do
  ...
end
```

### std functions

```
abs(nb)
sqrt,sin,cos,exp,ln,log etc.
print_number(nb)
input_number()
ceil(nb)
floor(nb)
random_int(min, max)
random_float(min, max)
type(var) -> return the type of a var as int
is_null(var)
is_number(var)
print_string(str)
print_newline()
print_ascii(nb)
```