User-defined types: Tracking issue #156
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Jul 24, 2024
This is the feature branch for enabling struct field access and mutation of linear fields. Closes #276, closes #280, and closes #156. The difficult bit is that we want to track linearity of individual struct fields separately (akin to Rust's partial moves): ```python @guppy.struct class MyStruct: q1: qubit q2: qubit x: int def main(s: MyStruct): q = h(s.q1) t = h(s.q2) # Using s.q2 is fine, only s.q1 has been used y = s.x + s.x # Classical fields can be used multiple times use(s) # Error: Linear fields of s have already been used ... ``` This is the plan: * We introduce a new notion called `Place`: A place is a description for a storage location of a local value that users can refer to in their program. Roughly, these are values that can be lowered to a static wire within the Hugr and are tracked separately when checking linearity. * For the purposes of this PR, a place is either a local variable or a field projection of another place that holds a struct. I.e. places are paths `a.b.c.d` of zero or more nested struct accesses. In the future, indexing into an array etc will also become a place. * During type checking, we figure out which AST nodes correspond to places and annotate them as such * For linearity checking, we run a liveness analysis pass that tracks usage and assignment of places across the CFG. This way, linearity of different struct fields is tracked individually. * When compiling to Hugr, we keep track of a mapping from places to wires/ports Tracked PRs: * #288: Precursor PR to generalise our program analysis framework to run on places in the future. * #289: Adds the `Place` type and implements the type checking logic to turn `ast.Name` and `ast.Attribute` nodes into places. * #290: Update linearity checker to operate on places instead of variables * #291: Lower places to Hugr * #292: Some missing pieces to handle nested functions correctlt * #293
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StructDefandStructType#159The text was updated successfully, but these errors were encountered: