Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Speed up typechecking of dict, set and list expressions
Typechecking of dict, set, and list literals currentlly goes through typechecking of the generic dict/set/list constructor internally. This is usually fine but becomes horrendously slow when the number of items is large: - for generic methods, `infer_arg_types_in_context` is called twice - `infer_arg_types_in_context` is O(n**2) where `n` is the number of arguments, which, in the case of a literal, is the number of items. Add an `O(n)` fast path for deriving the type of simple container literal expressions. This fast path only handle a subset of cases but it provides a tremendous speedup for the relatively common case of large literal constants. The real-world example that motivated this change is a 1889 lines long dict constant representing the parsed value of a mock JSON response from a 3rd party service, where typechecking previously took upwards of 50s and is now down to under 1s with this fast path.
- Loading branch information