M.V. Hutz
a3ee34732e
## Description The old architecture used a monolithic `main()` with a custom arg parser, an event-emitter-based runtime, and a plugin system for optional features. This PR rewrites the CLI and internal architecture to be modular, extensible, and built around a registry of interchangeable components. - Replace custom CLI arg parsing with Cobra subcommands (`convert`, `reduce`, `engine list`). - Introduce a registry system (`internal/registry`) for marshalers, codecs, and engines, with BFS-based conversion path resolution. - Add type-erased adapter layer (`internal/cli`) with `Repr`, `Engine`, `Process`, `Marshaler`, and `Conversion` interfaces wrapping generic `pkg/` types. - Replace the event-emitter-based `Runtime` with a simpler `Engine`/`Process` model (`pkg/engine`). - Add generic `Codec[T, U]` and `Marshaler[T]` interfaces (`pkg/codec`). - Merge `saccharine/token` sub-package into `saccharine` and rename scanner functions from `parse*` to `scan*`. - Make saccharine-to-lambda conversion bidirectional (encode and decode). - Add `lambda.Marshaler` and `saccharine.Marshaler` implementing `codec.Marshaler`. - Remove old infrastructure: `pkg/runtime`, `pkg/expr`, `internal/plugins`, `internal/statistics`. - Add `make lint` target and update golangci-lint config. ### Decisions - Cobra was chosen for the CLI framework to support nested subcommands and standard flag handling. - The registry uses BFS to find conversion paths between representations, allowing multi-hop conversions without hardcoding routes. - Type erasure via `cli.Repr` (wrapping `any`) enables the registry to work with heterogeneous types while keeping `pkg/` generics type-safe. - The old plugin/event system was removed entirely rather than adapted, since the new `Process` model can support hooks differently in the future. ## Benefits - Subcommands make the CLI self-documenting and easier to extend with new functionality. - The registry pattern decouples representations, conversions, and engines, making it trivial to add new ones. - BFS conversion routing means adding a single codec automatically enables transitive conversions. - Simpler `Engine`/`Process` model reduces complexity compared to the event-emitter runtime. - Consolidating the `token` sub-package reduces import depth and package sprawl. ## Checklist - [x] Code follows conventional commit format. - [x] Branch follows naming convention (`<type>/<description>`). Always use underscores. - [ ] Tests pass (if applicable). - [ ] Documentation updated (if applicable). Reviewed-on: #41 Co-authored-by: M.V. Hutz <git@maximhutz.me> Co-committed-by: M.V. Hutz <git@maximhutz.me>
101 lines
2.4 KiB
Go
101 lines
2.4 KiB
Go
package lambda
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import (
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"fmt"
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"git.maximhutz.com/max/lambda/pkg/set"
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)
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// Expression is the interface for all lambda calculus expression types.
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// It embeds the general expr.Expression interface for cross-mode compatibility.
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type Expression interface {
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fmt.Stringer
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// Substitute replaces all free occurrences of the target variable with the
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// replacement expression. Alpha-renaming is performed automatically to
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// avoid variable capture.
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Substitute(target string, replacement Expression) Expression
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// GetFree returns the set of all free variable names in the expression.
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// This function does not mutate the input expression.
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// The returned set is newly allocated and can be modified by the caller.
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GetFree() set.Set[string]
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// Rename replaces all occurrences of the target variable name with the new name.
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Rename(target string, newName string) Expression
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// IsFree returns true if the variable name n occurs free in the expression.
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// This function does not mutate the input expression.
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IsFree(n string) bool
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}
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/** ------------------------------------------------------------------------- */
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type Abstraction struct {
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parameter string
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body Expression
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}
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var _ Expression = Abstraction{}
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func (a Abstraction) Parameter() string {
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return a.parameter
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}
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func (a Abstraction) Body() Expression {
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return a.body
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}
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func (a Abstraction) String() string {
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return "\\" + a.parameter + "." + a.body.String()
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}
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func NewAbstraction(parameter string, body Expression) Abstraction {
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return Abstraction{parameter, body}
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}
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/** ------------------------------------------------------------------------- */
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type Application struct {
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abstraction Expression
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argument Expression
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}
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var _ Expression = Application{}
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func (a Application) Abstraction() Expression {
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return a.abstraction
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}
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func (a Application) Argument() Expression {
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return a.argument
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}
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func (a Application) String() string {
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return "(" + a.abstraction.String() + " " + a.argument.String() + ")"
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}
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func NewApplication(abstraction Expression, argument Expression) Application {
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return Application{abstraction, argument}
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}
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/** ------------------------------------------------------------------------- */
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type Variable struct {
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name string
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}
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var _ Expression = Variable{}
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func (v Variable) Name() string {
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return v.name
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}
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func (v Variable) String() string {
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return v.name
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}
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func NewVariable(name string) Variable {
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return Variable{name}
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}
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