readme: add syntax description and roadmap

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Michael Sippel 2024-05-01 17:07:47 +02:00
parent d7502e6af8
commit c59c0f3e5b
Signed by: senvas
GPG key ID: F96CF119C34B64A6

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@ -5,6 +5,8 @@ Rust Implementation of Ladder-Types (parsing, unification, rewriting, etc)
## Ladder Types
### Motivation
In order to implement complex datastructures and algorithms, usually
many layers of abstraction are built ontop of each other.
Consequently higher-level data types are encoded into lower-level data
@ -57,6 +59,50 @@ this:
1696093021:1696093039:1528324679:1539892301:1638141920:1688010253
```
### Syntax
In their core form, type-terms can be one of the following:
- (**Atomic Type**) | `SomeTypeName`
- (**Literal Integer**) | `0` | `1` | `2` | ...
- (**Literal Character**) | `'a'` | `'b'` | `'c'` | ...
- (**Literal String**) | `"abc"`
- (**Parameter Application**) | `<T1 T2>` given `T1` and `T2` are type-terms
- (**Ladder**) | `T1 ~ T2` given `T1` and `T2` are type-terms
Ontop of that, the following syntax-sugar is defined:
#### Complex Types
- `[ T ]` <===> `<Seq T>`
- `{ a:A b:B }` <===> `<Struct <"a" A> <"b" B>>`
- `a:A | b:B` <===> `<Enum <"a" A> <"b" B>>`
#### Function Types
- `A -> B` <===> `<Fn A B>`
#### Reference Types
- `*A` <===> `<Ptr A>`
- `&A` <===> `<ConstRef A>`
- `&!A` <===> `<MutRef A>`
### Equivalences
#### Currying
`<<A B> C>` <===> `<A B C>`
#### Ladder-Normal-Form
exhaustively apply `<A B~C>` => `<A B>~<A C>`
e.g.
- `[<Digit 10>~Char~Ascii]` ===> `[<Digit 10>]~[Char]~[Ascii]`
#### Parameter-Normal-Form
exhaustively apply `<A B>~<A C>` => `<A B~C>`
e.g.
`[<Digit 10>~Char~Ascii]` ===> `[<Digit 10>]~[Char]~[Ascii]`
## How to use this crate
```rust
@ -73,6 +119,19 @@ fn main() {
}
```
## Roadmap
- [x] (Un-)Parsing
- [x] (De-)Currying
- [x] Unification
- [x] Ladder-Normal-Form
- [x] Parameter-Normal-Form
- [ ] (De)-Sugaring
- [ ] Seq
- [ ] Enum
- [ ] Struct
- [ ] References
- [ ] Function
## License
[GPLv3](COPYING)