Files
lambda/pkg/lambda/rename.go
M.V. Hutz 9c7fb8ceba refactor: rename interpreter to runtime and use receiver methods (#39)
## Description

The codebase previously used "interpreter" terminology and standalone functions for expression operations.
This PR modernizes the architecture by renaming to "runtime" and converting operations to receiver methods.

- Rename `pkg/interpreter` to `pkg/runtime`.
- Move `ReduceOnce` to new `pkg/normalorder` package for reduction strategy isolation.
- Convert standalone functions (`Substitute`, `Rename`, `GetFree`, `IsFree`) to receiver methods on concrete expression types.
- Change `Set` from pointer receivers to value receivers for simpler usage.
- Update all references from "interpreter" to "runtime" terminology throughout the codebase.

### Decisions

- Operations like `Substitute`, `Rename`, `GetFree`, and `IsFree` are now methods on the `Expression` interface, implemented by each concrete type (`Variable`, `Abstraction`, `Application`).
- The `normalorder` package isolates the normal-order reduction strategy, allowing future reduction strategies to be added in separate packages.
- `Set` uses value receivers since Go maps are reference types and don't require pointer semantics.

## Benefits

- Cleaner API: `expr.Substitute(target, replacement)` instead of `Substitute(expr, target, replacement)`.
- Better separation of concerns: reduction strategies are isolated from expression types.
- Consistent terminology: "runtime" better reflects the execution model.
- Simpler `Set` usage without needing to manage pointers.

## Checklist

- [x] Code follows conventional commit format.
- [x] Branch follows naming convention (`<type>/<description>`). Always use underscores.
- [x] Tests pass (if applicable).
- [x] Documentation updated (if applicable).

Reviewed-on: #39
Co-authored-by: M.V. Hutz <git@maximhutz.me>
Co-committed-by: M.V. Hutz <git@maximhutz.me>
2026-01-18 20:52:34 +00:00

29 lines
697 B
Go

package lambda
// Rename replaces all occurrences of the target variable name with the new name.
func (e Variable) Rename(target string, newName string) Expression {
if e.Name() == target {
return NewVariable(newName)
}
return e
}
func (e Abstraction) Rename(target string, newName string) Expression {
newParam := e.Parameter()
if e.Parameter() == target {
newParam = newName
}
newBody := e.Body().Rename(target, newName)
return NewAbstraction(newParam, newBody)
}
func (e Application) Rename(target string, newName string) Expression {
newAbs := e.Abstraction().Rename(target, newName)
newArg := e.Argument().Rename(target, newName)
return NewApplication(newAbs, newArg)
}