Implement RFC 0028: make untyped R functions callable - #30
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fabriceHategekimana merged 1 commit intoSep 12, 2026
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`Lang::RFunction` (`function(a, b) { ... }`) now types as a real
`(Any, ..., Any) -> Any` function with n parameters, instead of the
0-ary `Type::UnknownFunction` placeholder that made any call with
arguments a type error. `Type::UnknownFunction` (used for preloaded
untyped base-R builtins like `Position`, `t`, `Reduce`) becomes
variadic for the same reason — fixing only `RFunction` would leave
the bug reachable through every untyped base-R name.
- `processes/type_checking/mod.rs`: `Lang::RFunction`'s typing rule
builds a `Type::Function` with n `Any` params -> `Any`.
- `components/type/mod.rs` and `components/type/function_type.rs`:
`Type::UnknownFunction`'s conversion to `FunctionType` is now a
single variadic `Any` parameter -> `Any`.
- `components/error_message/type_error.rs`: new `TypeError::
UntypedFunctionArity` (T044) replaces the confusing "no signature
matches () -> UnknownFunction" message with the RFC's proposed
wording when an untyped function is called with the wrong arity.
- `processes/type_checking/function_application.rs`: wires the new
error in, using `FunctionType::is_r_function()` to detect the
untyped-function shape.
- `cases/0062-0064`: regression cases for the callable case, the
arity error message, and the preloaded-builtin case.
Bumps the `guard_any_type_call_count_is_tracked` baseline 19 -> 21:
two new `any_type()` calls in the `RFunction` typing arm, which is
the RFC's whole point, not a silent degradation.
Tracking issue: #29
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ETPqhgWqDMt7UaUQXdxJmN
fabriceHategekimana
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September 12, 2026 07:45
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Summary
Implements the accepted RFC 0028 (tracking: #29): an untyped R function (
function(a, b) { ... }) becomes callable, checked on arity only, with its result typedAny.Lang::RFunctionnow types as a real(Any, ..., Any) -> Anyfunction withnparameters (parameters.len()), instead of the 0-aryType::UnknownFunctionplaceholder that rejected any call with arguments.Type::UnknownFunction(preloaded untyped base-R builtins —Position,t,Reduce, …) becomes variadic for the same reason: fixing onlyRFunctionwould leave the same bug reachable through every untyped base-R name (the RFC calls this "the load-bearing half").TypeError::UntypedFunctionArity(T044) replaces the old confusingNo signature of function 'x' matches this call ... () -> UnknownFunctionmessage with the RFC's proposed wording when an untyped call's arity is wrong:cases/0062'sR/main.Rrule.cases/entries per the RFC's implementation checklist: the callable case, the arity error message, and the preloaded-builtin case.Test plan
cargo test --workspace— 869 tests pass (0 failures)typr case run— 47 PASS, 0 REGRESS (3 new cases added, all PASS)docs/philosophy/intro.md'smy_addition) now compilesPosition(1, 2)now compilesmy_addition(num1, num2) |> as.Integer())Not in scope here (left for follow-up, per the RFC checklist):
syntaxe.mdand thetypr.github.iodocumentation update (docs/philosophy/intro.md'snoplaygroundremoval) — no syntax changed, and the docs live in a separate repo.🤖 Generated with Claude Code
https://claude.ai/code/session_01ETPqhgWqDMt7UaUQXdxJmN