if we went back to it we would definitely move to Rust.
Conversation
Cool! I'll have a look and see if there's anything interesting I can learn!
1
1
mind if we leave our thoughts on your thing as we read through the spec?
1
Sadly I let the spec get out of date 😭
2
hey, it's better than us - we never managed to put together a good easily-browseable version of the spec that doesn't need to be read in Scrivener. (though you will find HTML exports in that repo)
1
hmmm, so we think it's in a sense a mistake to have struct types as a primitive in the language. you can build them out of product types, so it doesn't make sense to have both. you can have pre-built structs as a library feature rather than a language feature.
2
1
The issue is that these are 'dependent struct types', so they are more 'dependent sums' than 'product types'. I'm still on the fence as to if I want them to be nominal definitions though.
1
1
I'm also thinking I might want to separate out 'dependent sequence formats' from 'dependent structs' - this might help me with some of the phase problems I was having (mentioned in another tweet).
1
1
when you say phase problems, what do you mean exactly?
1
Ie. how to deal with the interpretation of 'formats descriptions' into the host language. Eg. do you mean a U32Be or an { x : Int | x in 0..u32_max }? It shows up where you have dependent types though. Gotta head off for a bit, but I can try to explain later!
2
1
Like, the best I can come up with right now is that U32Be is not really a type - more term that describes a type and a method of parsing that type that is constrained to live at compile time.
You could imagine allowing these format descriptions to live at runtime, say if you wanted to describe formats dynamically, but forcing them to live statically helps me in terms of building a compiler, at this stage!
1
notionally, your user can always build their own version that exists at runtime. (or if they can't, your primitives aren't powerful enough and should be fixed.)
1
Show replies
we thought about introducing the concept of an explicit transformation function that would convert between lower-level and higher-level representations. that could also be useful in cases where, for example, an existing file format incorporates a compression codec.
1
1
it's just not immediately clear to us whether that is reinventing something that already exists.
1