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Module desugar

graphcal_compiler

Module desugar 

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Generic desugaring pipeline.

Transforms File<Raw> (parser output, with all surface sugar) into File<Desugared> (canonical form consumed by name resolution, IR lowering, TIR, and evaluation).

§Architecture

Each surface sugar implements DesugarSugar — a node-level transform that maps one raw sugar variant to its desugared equivalent. The generic walker in this module traverses the AST, dispatching Sugar(_) arms to the appropriate DesugarSugar impl while every other variant is rebuilt phase-by-phase with its children desugared recursively.

File<Raw> ──┬─► (walker) ──┬─► File<Desugared>
            │               │
            ├─ MultiDecl ───┘ via DesugarSugar
            └─ TableLiteral ──► (desugar to MapLiteral)

§Adding a new customer

  1. Add a variant to crate::syntax::ast::RawDeclSugar or crate::syntax::ast::RawExprSugar.
  2. Implement DesugarSugar for that variant in a submodule of this module.
  3. Wire it into the walker’s Sugar(_) dispatch.

No changes to downstream consumers are needed — they only see File<Desugared> and never observed the sugar in the first place.

§Span fidelity

Desugaring preserves source spans: every synthesized node carries the span of the surface construct it came from. Diagnostics emitted on desugared AST still point at the original source.

Modules§

convert
From<X<Raw>> for X<Desugared> impls.
desugared_ast
Type aliases pinning every phase-parameterized AST node to crate::syntax::phase::Desugared.

Traits§

DesugarSugar
Single-node desugaring step.