nadrieril / dhall-rust Goto Github PK

According to the standard, dumplicate imports should only be resolved once, so imports should be cached in a hashmap as we resolve them.

Blocked by rust-lang/rust#36353 (see rust-lang/rust#23121)

• box_patterns: For nested matching. Removed a while ago and replaced with ExprF and appropriate (un)rolling.
• slice_patterns: Used a lot in binary decoder. Would be a huge pain to do without.
• proc_macro_hygiene. Enables dhall::expr!() and friends in expressions. Can be circumvented; see #52.
• bind_by_move_pattern_guards: Used to avoid rust-lang/rust#59803. Removed in 350d924.
• custom_inner_attributes: Used to prevent rustfmt from messing up the list of tests. Will be removed when the test lists gets generated automatically.
• label_break_value: Mild convenience; could be easily removed.
• non_exhaustive: Used to somewhat limit API surface; could be easily removed.
• inner_deref: just for convenience.
• never_type: convenience, alternative is rolling own empty enum. Should get stabilized eventually.
• try_blocks: For parser macros. Could be avoided using anonymous closures.
• exhaustive_patterns: Small convenience. Could be traded for some verbosity.
• proc_macro_hygiene: Used in parser. Would need some advanced hackery to do without.
• drain_filter: Small convenience. Could be traded for some verbosity.
• type_alias_enum_variant: has been stabilized in 1.37.0

Right now the OptionalLit AST node stores a Vec of subexpressions. Since an Optional value can only have 0 or 1 values, storing the optional subexpression in an Option<Box<Expr<_, _>>> makes more sense.
Doing this change will affect most of the parts of the project, so it's not trivial, but should give you a good overview of the different parts of it. It shouldn't be too hard to fix with the help of Rust and the tests.

prop_equals depends on the keys being sorted for now

Dhall supports importing from remote URLs. This is slightly tricky to support because remote imports can themselves import relative files. The standard gives details on how this should work: https://github.com/dhall-lang/dhall-lang/blob/master/standard/semantics.md#chaining-imports (feel free to ignore the thing about canonicalizing directories for now).
Headers, CORS headers and referential sanity check are out of scope for now.

https://docs.rs/quick-error/1.2.2/quick_error/
https://docs.rs/error-chain/0.12.0/error_chain/

Almost there: #42.
Waiting for dhall-lang/dhall-lang#455 and dhall-lang/dhall-lang#452 to be merged.