lone-lang / lone Goto Github PK

Hi! I haven't used the project yet, so feel free to dismiss the ideas. But here goes nothing: what about supporting Windows and Mac too, using the techniques from https://justine.lol/ape.html ?

Hi there! I came from your Reddit post and found this project fascinating.

While reading the sources, I've found the header include/lone/types.h, which uses a common technique of tagged unions. Most notably, struct lone_value:

struct lone_value {
	// Auxiliary data...

	enum lone_type type;

	union {
		struct lone_module module;
		struct lone_function function;
		struct lone_primitive primitive;
		struct lone_list list;
		struct lone_vector vector;
		struct lone_table table;
		struct lone_bytes bytes;
		struct lone_pointer pointer;
		long integer;
	};
};

The downside of this approach is that it's possible to mess up during case analysis by 1) not checking a tag, or by 2) checking a tag A and then using B. The compiler cannot check this automatically, causing the bug to silently creep into the final executable.

Instead of managing tagged unions manually, I would suggest using Datatype99, which is a header-only library designed specifically to deal with the problem of tagged unions. struct lone_value would look as follows ¹:

datatype(
    LoneValue,
    (LoneModule, struct lone_module),
    (LoneFunction, struct lone_function),
    (LonePrimitive, struct lone_primitive),
    (LoneList, struct lone_list),
    (LoneVector, struct lone_vector),
    (LoneTable, struct lone_table),
    (LoneBytes, struct lone_bytes),
    (LonePointer, struct lone_pointer),
    (LoneInteger, long)
);

And case-analyzed as follows:

void handle(LoneValue value) {
    match(value) {
        of(LoneModule, module) { /* ... */ }
        of(LoneFunction, function) { /* ... */ }
        of(LonePrimitive, primitive) { /* ... */ }
        of(LoneList, list) { /* ... */ }
        of(LoneVector, vector) { /* ... */ }
        of(LoneTable, table) { /* ... */ }
        of(LoneBytes, bytes) { /* ... */ }
        of(LonePointer, pointer) { /* ... */ }
        of(LoneInteger, integer) { /* ... */ }
    }
}

Since of explicitly provides a variable binding, such as module or function, it's now much harder to make a mistake. The datatype encoding is also more concise than the corresponding tagged union representation, since the former defines both enum lone_type and struct lone_value ².

Since Datatype99 has no run-time dependencies (not even the C standard library), and has a transparent and formally specified semantics, I think it might be a great fit for Lone ³.

Let me know if you have any thoughts or questions, which I should be able to answer.

I appreciate it may not be done yet, but the ability to make fat UI applications (or not) would be a great addition to the list.

Context: QML is interesting, but I think they missed an opportunity - https://paulhammant.com/2016/11/15/qmls-squandered-opportunity/. In that post I talk of a calculator and there are loads of attempts at making it as a demo in different techs. The web has many, and one or two are "single file" for that. Of course Lisp is the grandpappy language for elegant pseudo-declarative apps - https://paulhammant.com/2013/03/28/interface-builders-alternative-lisp-timeline so I'd imagine it was possible and terse/elegant. That's racing ahead as lone-lang should note whether it can do UI or not :)

Great work though!

GCC stack smashing protection references:

• GCC Internals
• OSDev Wiki

When stack smashing protection is turned on, the compiler generates some fairly simple code:

extern uintptr_t __stack_chk_guard;
noreturn void __stack_chk_fail(void);

void foo(const char* str)
{
	uintptr_t canary = __stack_chk_guard;

	/* ... */

	if ( (canary = canary ^ __stack_chk_guard) != 0 )
		__stack_chk_fail();
}

It looks like all we have to do is initialize __stack_chk_guard to a random number and provide a __stack_chk_fail function which exits the program. Linux provides 16 random bytes to every process via the auxiliary vector and lone already uses those to initialize its hash functions. It should be possible to use those random bytes to initialize the stack canary as well.

Originally posted by @matheusmoreira in #3 (comment)