chermehdi / comet

A programming language implementation in Go.

Hi there, I'm Mehdi welcome to my profile.

• I am a Software Engineer, Living in London, and a Huge Rust and Go enthusiast.

• Mostly interested in projects involving (but not limited to) Compilers, Programming languages, Developer tools ...

• I want to contribute more to open source projects (other than the ones that I create), and upload more educational videos and live streams to Youtube and hopefully blog more regularly.

• I am pationate about teaching people what I learned, So if you have a project involving teaching people new things, feel free to reach out.

comet's Issues

Bug in toString a CometArray

I got a panic after using toString(anArray), because the builtin function toString is not supported for CometArray

>> var cc = [1, 2, 3]
CometNop
>> cc
[CometInt(1), CometInt(2), CometInt(3)]
>> println(cc)
&{3 [0xc0001020b0 0xc0001020b8 0xc0001020c0]}
CometNop
>> toString(cc)
panic: All types should have been exhausted!!

goroutine 1 [running]:
github.com/chermehdi/comet/std.ToString(0x667a58, 0xc0001042a0, 0x1)

I think, We have to implement two functions to represent objects as strings, for example:

• A debug function should return: CometArray[CometInt(1), CometInt(2), CometInt(3)]
• The toString function should return just [1, 2, 3]

Add the ability to lex/parse other number formats

Comet only considers numbers to only be represented in decimal format, which is not realistic in a programming language.

We expect Comet to be able to lex and parse numbers of binary, hex, octal format as well:

var a = 0xcafebabe
var b = 0b10100000
var c = 012

Bug in variable declaration

I tried this:

var a = 7
var a = "Test"

and it works, it erase old value of a instead of returning a CometError.

We have to fix this and I think, We must implement something to not allowing variable shadowing either, it's a source of bugs.

The printf built-in function does not work as expected

I tried printf("Hi\n") in the REPL and the result was Hi\n%!(EXTRA []interface {}=[])CometNop.

So, the issues are:

• printf does not interpret special characters like \t or \n.
• if we print something without other arguments, printf print the extra empty []CometObject that was intended to be full of other arguments.

Add better toString representation

Built-in types need better toString representation for debugging purposes.

Values and especially functions only show the type, we want something that shows the type signature as well.

Better Error reporting

Comet should provide a mechanism for better error reporting, this should be accomplished in multiple steps:

1. Make all the current error messages contain as much information as available / needed.
2. Make a dictionary of all the available errors and give them numbers for future pointers in the docs.
3. Print spans for where the error happened.

Bug in variable assign expression

I tried this:

// variable 'a' is not declared before
a = 50

and it return CometInt(50) instead of an error.

Built-ins functions are not reserved keywords or known identifiers

I tried that:

>> println
Comet error:

        Identifier (println) is not bounded to any value, have you tried declaring it?
>> var println = 5
CometNop
>> println
CometInt(5)
>> println("Hello, World!")
Hello, World!
CometNop

As a Python developer, I'm expecting that:

>> println
<func builtins.println>

They are two options:

• Let the developer overwrite builtins functions like user's functions:

>> func add(n) {2*n}
<func add(n)>
>> add = 70
CometInt(70)

• Make builtins functions reserved keywords