This commit introduces bidirectional type inference, enabling the
compiler to infer lambda parameter types based on the context of their
usage. This is particularly useful for functions like `pipe`, where a
lambda's signature can be deduced from the types of the streams it
operates on.
Key changes include:
- **`extract_lambda_param_hints` function:** This new helper function in
`type_checker.rs` is responsible for extracting expected parameter
types for a lambda based on the callee's signature and already known
argument types.
- **`check_lambda_with_param_hints` function:** This function allows
type-checking a lambda node using provided parameter type hints,
preserving upvalue types from the enclosing scope.
- **Call expression type checking:** The `check_call` function now
phases its argument type checking. Non-lambda arguments are typed
first, and then lambda arguments are typed using hints derived from
`extract_lambda_param_hints`.
- **`pipe_arg_hint_resolver`:** This new resolver for the `pipe`
function's `PolymorphicFn` type allows it to provide specific type
hints for its lambda argument based on the types of its stream inputs
(single stream, vector of streams, or tuple of streams).
- **`StaticType::PolymorphicFn` update:** The `PolymorphicFn` enum
variant has been extended to include `resolve_arg_hints`, enabling
functions to provide lambda parameter hints during bidirectional type
inference.
- **New tests:** Added tests to verify the correct inference of lambda
parameters for `pipe` with vector and tuple inputs, ensuring that
inner stream types are correctly propagated. Also, a test to confirm
`pipe` with an optional return still produces `Stream(Float)`.
Brummel
a5c3f3da04