lang

type CallFunc func(context.Context, *apivalues.Value, map[string]*apivalues.Value, []*apivalues.Value, *apilang.RunSummary) (*apivalues.Value, error)

type Catalog interface {
	Register(name string, l CatalogLang)

	// Returns lang name -> extensions.
	List() map[string][]string

	// Return a lang for the given name and scope.
	// If scope is empty, return a new lang.
	Acquire(name, scope string) (Lang, error)
}

type CatalogLang struct {
	New  NewLangFunc
	Exts []string // extensions without the prefix dot.
}

type ErrCanceled struct{ CallStack []*apiprogram.CallFrame }

type ErrMissingDependencies []*apiprogram.Path

type Lang interface {
	IsCompilerVersionSupported(context.Context, string) (bool, error)

	CompileModule(
		_ context.Context,
		path *apiprogram.Path,
		src []byte,
		predecls []string,
	) (*apiprogram.Module, error)

	GetModuleDependencies(context.Context, *apiprogram.Module) ([]*apiprogram.Path, error)

	// In case of cancellation, will return ErrCanceled{Callstack: ...}.
	RunModule(
		ctx context.Context,
		env *RunEnv,
		mod *apiprogram.Module,
	) (map[string]*apivalues.Value, *apilang.RunSummary, error)

	// In case of cancellation, will return ErrCanceled{Callstack: ...}.
	CallFunction(
		ctx context.Context,
		env *RunEnv,
		fn *apivalues.Value,
		args []*apivalues.Value,
		kws map[string]*apivalues.Value,
	) (*apivalues.Value, *apilang.RunSummary, error)
}

type LoadFunc func(context.Context, *apiprogram.Path) (map[string]*apivalues.Value, *apilang.RunSummary, error)

type NewLangFunc func(l L.L, name string) (Lang, error)

type PrintFunc func(string)

type RunEnv struct {
	Scope    string
	Predecls map[string]*apivalues.Value

	// TODO: need to limit size of what can passed in this funcs to prevet DOS.
	Print PrintFunc
	Load  LoadFunc // not relevant for function calls.
	Call  CallFunc
}