move repl.cc to libcmd for linkage

src/libcmd/repl.cc

@@ -0,0 +1,832 @@
+#include <iostream>
+#include <cstdlib>
+#include <cstring>
+#include <climits>
+
+#include <setjmp.h>
+
+#ifdef READLINE
+#include <readline/history.h>
+#include <readline/readline.h>
+#else
+// editline < 1.15.2 don't wrap their API for C++ usage
+// (added in https://github.com/troglobit/editline/commit/91398ceb3427b730995357e9d120539fb9bb7461).
+// This results in linker errors due to to name-mangling of editline C symbols.
+// For compatibility with these versions, we wrap the API here
+// (wrapping multiple times on newer versions is no problem).
+extern "C" {
+#include <editline.h>
+}
+#endif
+
+#include "ansicolor.hh"
+#include "shared.hh"
+#include "eval.hh"
+#include "eval-inline.hh"
+#include "attr-path.hh"
+#include "store-api.hh"
+#include "common-eval-args.hh"
+#include "get-drvs.hh"
+#include "derivations.hh"
+#include "affinity.hh"
+#include "globals.hh"
+#include "command.hh"
+#include "finally.hh"
+#include "markdown.hh"
+
+#if HAVE_BOEHMGC
+#define GC_INCLUDE_NEW
+#include <gc/gc_cpp.h>
+#endif
+
+namespace nix {
+
+struct NixRepl
+    #if HAVE_BOEHMGC
+    : gc
+    #endif
+{
+    string curDir;
+    ref<EvalState> state;
+    Bindings * autoArgs;
+
+    Strings loadedFiles;
+
+    const static int envSize = 32768;
+    StaticEnv staticEnv;
+    Env * env;
+    int displ;
+    StringSet varNames;
+
+    const Path historyFile;
+
+    NixRepl(ref<EvalState> state);
+    ~NixRepl();
+    void mainLoop(const std::vector<std::string> & files);
+    StringSet completePrefix(string prefix);
+    bool getLine(string & input, const std::string &prompt);
+    StorePath getDerivationPath(Value & v);
+    bool processLine(string line);
+    void loadFile(const Path & path);
+    void initEnv();
+    void reloadFiles();
+    void addAttrsToScope(Value & attrs);
+    void addVarToScope(const Symbol & name, Value * v);
+    Expr * parseString(string s);
+    void evalString(string s, Value & v);
+
+    typedef set<Value *> ValuesSeen;
+    std::ostream & printValue(std::ostream & str, Value & v, unsigned int maxDepth);
+    std::ostream & printValue(std::ostream & str, Value & v, unsigned int maxDepth, ValuesSeen & seen);
+};
+
+
+string removeWhitespace(string s)
+{
+    s = chomp(s);
+    size_t n = s.find_first_not_of(" \n\r\t");
+    if (n != string::npos) s = string(s, n);
+    return s;
+}
+
+
+NixRepl::NixRepl(ref<EvalState> state)
+    : state(state)
+    , staticEnv(false, &state->staticBaseEnv)
+    , historyFile(getDataDir() + "/nix/repl-history")
+{
+    curDir = absPath(".");
+}
+
+
+NixRepl::~NixRepl()
+{
+    write_history(historyFile.c_str());
+}
+
+static NixRepl * curRepl; // ugly
+
+static char * completionCallback(char * s, int *match) {
+  auto possible = curRepl->completePrefix(s);
+  if (possible.size() == 1) {
+    *match = 1;
+    auto *res = strdup(possible.begin()->c_str() + strlen(s));
+    if (!res) throw Error("allocation failure");
+    return res;
+  } else if (possible.size() > 1) {
+    auto checkAllHaveSameAt = [&](size_t pos) {
+      auto &first = *possible.begin();
+      for (auto &p : possible) {
+        if (p.size() <= pos || p[pos] != first[pos])
+          return false;
+      }
+      return true;
+    };
+    size_t start = strlen(s);
+    size_t len = 0;
+    while (checkAllHaveSameAt(start + len)) ++len;
+    if (len > 0) {
+      *match = 1;
+      auto *res = strdup(std::string(*possible.begin(), start, len).c_str());
+      if (!res) throw Error("allocation failure");
+      return res;
+    }
+  }
+
+  *match = 0;
+  return nullptr;
+}
+
+static int listPossibleCallback(char *s, char ***avp) {
+  auto possible = curRepl->completePrefix(s);
+
+  if (possible.size() > (INT_MAX / sizeof(char*)))
+    throw Error("too many completions");
+
+  int ac = 0;
+  char **vp = nullptr;
+
+  auto check = [&](auto *p) {
+    if (!p) {
+      if (vp) {
+        while (--ac >= 0)
+          free(vp[ac]);
+        free(vp);
+      }
+      throw Error("allocation failure");
+    }
+    return p;
+  };
+
+  vp = check((char **)malloc(possible.size() * sizeof(char*)));
+
+  for (auto & p : possible)
+    vp[ac++] = check(strdup(p.c_str()));
+
+  *avp = vp;
+
+  return ac;
+}
+
+namespace {
+    // Used to communicate to NixRepl::getLine whether a signal occurred in ::readline.
+    volatile sig_atomic_t g_signal_received = 0;
+
+    void sigintHandler(int signo) {
+        g_signal_received = signo;
+    }
+}
+
+void NixRepl::mainLoop(const std::vector<std::string> & files)
+{
+    string error = ANSI_RED "error:" ANSI_NORMAL " ";
+    std::cout << "Welcome to Nix version " << nixVersion << ". Type :? for help." << std::endl << std::endl;
+
+    if (!files.empty()) {
+        for (auto & i : files)
+            loadedFiles.push_back(i);
+
+        reloadFiles();
+        if (!loadedFiles.empty()) std::cout << std::endl;
+    }
+
+    // Allow nix-repl specific settings in .inputrc
+    rl_readline_name = "nix-repl";
+    createDirs(dirOf(historyFile));
+#ifndef READLINE
+    el_hist_size = 1000;
+#endif
+    read_history(historyFile.c_str());
+    curRepl = this;
+#ifndef READLINE
+    rl_set_complete_func(completionCallback);
+    rl_set_list_possib_func(listPossibleCallback);
+#endif
+
+    std::string input;
+
+    while (true) {
+        // When continuing input from previous lines, don't print a prompt, just align to the same
+        // number of chars as the prompt.
+        if (!getLine(input, input.empty() ? "nix-repl> " : "          "))
+            break;
+
+        try {
+            if (!removeWhitespace(input).empty() && !processLine(input)) return;
+        } catch (ParseError & e) {
+            if (e.msg().find("unexpected end of file") != std::string::npos) {
+                // For parse errors on incomplete input, we continue waiting for the next line of
+                // input without clearing the input so far.
+                continue;
+            } else {
+              printMsg(lvlError, e.msg());
+            }
+        } catch (Error & e) {
+            printMsg(lvlError, e.msg());
+        } catch (Interrupted & e) {
+            printMsg(lvlError, e.msg());
+        }
+
+        // We handled the current input fully, so we should clear it
+        // and read brand new input.
+        input.clear();
+        std::cout << std::endl;
+    }
+}
+
+
+bool NixRepl::getLine(string & input, const std::string &prompt)
+{
+    struct sigaction act, old;
+    sigset_t savedSignalMask, set;
+
+    auto setupSignals = [&]() {
+        act.sa_handler = sigintHandler;
+        sigfillset(&act.sa_mask);
+        act.sa_flags = 0;
+        if (sigaction(SIGINT, &act, &old))
+            throw SysError("installing handler for SIGINT");
+
+        sigemptyset(&set);
+        sigaddset(&set, SIGINT);
+        if (sigprocmask(SIG_UNBLOCK, &set, &savedSignalMask))
+            throw SysError("unblocking SIGINT");
+    };
+    auto restoreSignals = [&]() {
+        if (sigprocmask(SIG_SETMASK, &savedSignalMask, nullptr))
+            throw SysError("restoring signals");
+
+        if (sigaction(SIGINT, &old, 0))
+            throw SysError("restoring handler for SIGINT");
+    };
+
+    setupSignals();
+    char * s = readline(prompt.c_str());
+    Finally doFree([&]() { free(s); });
+    restoreSignals();
+
+    if (g_signal_received) {
+        g_signal_received = 0;
+        input.clear();
+        return true;
+    }
+
+    if (!s)
+      return false;
+    input += s;
+    input += '\n';
+    return true;
+}
+
+
+StringSet NixRepl::completePrefix(string prefix)
+{
+    StringSet completions;
+
+    size_t start = prefix.find_last_of(" \n\r\t(){}[]");
+    std::string prev, cur;
+    if (start == std::string::npos) {
+        prev = "";
+        cur = prefix;
+    } else {
+        prev = std::string(prefix, 0, start + 1);
+        cur = std::string(prefix, start + 1);
+    }
+
+    size_t slash, dot;
+
+    if ((slash = cur.rfind('/')) != string::npos) {
+        try {
+            auto dir = std::string(cur, 0, slash);
+            auto prefix2 = std::string(cur, slash + 1);
+            for (auto & entry : readDirectory(dir == "" ? "/" : dir)) {
+                if (entry.name[0] != '.' && hasPrefix(entry.name, prefix2))
+                    completions.insert(prev + dir + "/" + entry.name);
+            }
+        } catch (Error &) {
+        }
+    } else if ((dot = cur.rfind('.')) == string::npos) {
+        /* This is a variable name; look it up in the current scope. */
+        StringSet::iterator i = varNames.lower_bound(cur);
+        while (i != varNames.end()) {
+            if (string(*i, 0, cur.size()) != cur) break;
+            completions.insert(prev + *i);
+            i++;
+        }
+    } else {
+        try {
+            /* This is an expression that should evaluate to an
+               attribute set.  Evaluate it to get the names of the
+               attributes. */
+            string expr(cur, 0, dot);
+            string cur2 = string(cur, dot + 1);
+
+            Expr * e = parseString(expr);
+            Value v;
+            e->eval(*state, *env, v);
+            state->forceAttrs(v);
+
+            for (auto & i : *v.attrs) {
+                string name = i.name;
+                if (string(name, 0, cur2.size()) != cur2) continue;
+                completions.insert(prev + expr + "." + name);
+            }
+
+        } catch (ParseError & e) {
+            // Quietly ignore parse errors.
+        } catch (EvalError & e) {
+            // Quietly ignore evaluation errors.
+        } catch (UndefinedVarError & e) {
+            // Quietly ignore undefined variable errors.
+        }
+    }
+
+    return completions;
+}
+
+
+bool isVarName(const string & s)
+{
+    if (s.size() == 0) return false;
+    char c = s[0];
+    if ((c >= '0' && c <= '9') || c == '-' || c == '\'') return false;
+    for (auto & i : s)
+        if (!((i >= 'a' && i <= 'z') ||
+              (i >= 'A' && i <= 'Z') ||
+              (i >= '0' && i <= '9') ||
+              i == '_' || i == '-' || i == '\''))
+            return false;
+    return true;
+}
+
+
+StorePath NixRepl::getDerivationPath(Value & v) {
+    auto drvInfo = getDerivation(*state, v, false);
+    if (!drvInfo)
+        throw Error("expression does not evaluate to a derivation, so I can't build it");
+    Path drvPathRaw = drvInfo->queryDrvPath();
+    if (drvPathRaw == "")
+        throw Error("expression did not evaluate to a valid derivation (no drv path)");
+    StorePath drvPath = state->store->parseStorePath(drvPathRaw);
+    if (!state->store->isValidPath(drvPath))
+        throw Error("expression did not evaluate to a valid derivation (invalid drv path)");
+    return drvPath;
+}
+
+
+bool NixRepl::processLine(string line)
+{
+    if (line == "") return true;
+
+    string command, arg;
+
+    if (line[0] == ':') {
+        size_t p = line.find_first_of(" \n\r\t");
+        command = string(line, 0, p);
+        if (p != string::npos) arg = removeWhitespace(string(line, p));
+    } else {
+        arg = line;
+    }
+
+    if (command == ":?" || command == ":help") {
+        // FIXME: convert to Markdown, include in the 'nix repl' manpage.
+        std::cout
+             << "The following commands are available:\n"
+             << "\n"
+             << "  <expr>        Evaluate and print expression\n"
+             << "  <x> = <expr>  Bind expression to variable\n"
+             << "  :a <expr>     Add attributes from resulting set to scope\n"
+             << "  :b <expr>     Build derivation\n"
+             << "  :e <expr>     Open the derivation in $EDITOR\n"
+             << "  :i <expr>     Build derivation, then install result into current profile\n"
+             << "  :l <path>     Load Nix expression and add it to scope\n"
+             << "  :p <expr>     Evaluate and print expression recursively\n"
+             << "  :q            Exit nix-repl\n"
+             << "  :r            Reload all files\n"
+             << "  :s <expr>     Build dependencies of derivation, then start nix-shell\n"
+             << "  :t <expr>     Describe result of evaluation\n"
+             << "  :u <expr>     Build derivation, then start nix-shell\n"
+             << "  :doc <expr>   Show documentation of a builtin function\n";
+    }
+
+    else if (command == ":a" || command == ":add") {
+        Value v;
+        evalString(arg, v);
+        addAttrsToScope(v);
+    }
+
+    else if (command == ":l" || command == ":load") {
+        state->resetFileCache();
+        loadFile(arg);
+    }
+
+    else if (command == ":r" || command == ":reload") {
+        state->resetFileCache();
+        reloadFiles();
+    }
+
+    else if (command == ":e" || command == ":edit") {
+        Value v;
+        evalString(arg, v);
+
+        Pos pos;
+
+        if (v.type() == nPath || v.type() == nString) {
+            PathSet context;
+            auto filename = state->coerceToString(noPos, v, context);
+            pos.file = state->symbols.create(filename);
+        } else if (v.isLambda()) {
+            pos = v.lambda.fun->pos;
+        } else {
+            // assume it's a derivation
+            pos = findDerivationFilename(*state, v, arg);
+        }
+
+        // Open in EDITOR
+        auto args = editorFor(pos);
+        auto editor = args.front();
+        args.pop_front();
+        runProgram(editor, true, args);
+
+        // Reload right after exiting the editor
+        state->resetFileCache();
+        reloadFiles();
+    }
+
+    else if (command == ":t") {
+        Value v;
+        evalString(arg, v);
+        std::cout << showType(v) << std::endl;
+
+    } else if (command == ":u") {
+        Value v, f, result;
+        evalString(arg, v);
+        evalString("drv: (import <nixpkgs> {}).runCommand \"shell\" { buildInputs = [ drv ]; } \"\"", f);
+        state->callFunction(f, v, result, Pos());
+
+        StorePath drvPath = getDerivationPath(result);
+        runProgram(settings.nixBinDir + "/nix-shell", true, {state->store->printStorePath(drvPath)});
+    }
+
+    else if (command == ":b" || command == ":i" || command == ":s") {
+        Value v;
+        evalString(arg, v);
+        StorePath drvPath = getDerivationPath(v);
+        Path drvPathRaw = state->store->printStorePath(drvPath);
+
+        if (command == ":b") {
+            /* We could do the build in this process using buildPaths(),
+               but doing it in a child makes it easier to recover from
+               problems / SIGINT. */
+            try {
+                runProgram(settings.nixBinDir + "/nix", true, {"build", "--no-link", drvPathRaw});
+                auto drv = state->store->readDerivation(drvPath);
+                std::cout << std::endl << "this derivation produced the following outputs:" << std::endl;
+                for (auto & i : drv.outputsAndOptPaths(*state->store))
+                    std::cout << fmt("  %s -> %s\n", i.first, state->store->printStorePath(*i.second.second));
+            } catch (ExecError &) {
+            }
+        } else if (command == ":i") {
+            runProgram(settings.nixBinDir + "/nix-env", true, {"-i", drvPathRaw});
+        } else {
+            runProgram(settings.nixBinDir + "/nix-shell", true, {drvPathRaw});
+        }
+    }
+
+    else if (command == ":p" || command == ":print") {
+        Value v;
+        evalString(arg, v);
+        printValue(std::cout, v, 1000000000) << std::endl;
+    }
+
+    else if (command == ":q" || command == ":quit")
+        return false;
+
+    else if (command == ":doc") {
+        Value v;
+        evalString(arg, v);
+        if (auto doc = state->getDoc(v)) {
+            std::string markdown;
+
+            if (!doc->args.empty() && doc->name) {
+                auto args = doc->args;
+                for (auto & arg : args)
+                    arg = "*" + arg + "*";
+
+                markdown +=
+                    "**Synopsis:** `builtins." + (std::string) (*doc->name) + "` "
+                    + concatStringsSep(" ", args) + "\n\n";
+            }
+
+            markdown += trim(stripIndentation(doc->doc));
+
+            std::cout << renderMarkdownToTerminal(markdown);
+        } else
+            throw Error("value does not have documentation");
+    }
+
+    else if (command != "")
+        throw Error("unknown command '%1%'", command);
+
+    else {
+        size_t p = line.find('=');
+        string name;
+        if (p != string::npos &&
+            p < line.size() &&
+            line[p + 1] != '=' &&
+            isVarName(name = removeWhitespace(string(line, 0, p))))
+        {
+            Expr * e = parseString(string(line, p + 1));
+            Value *v = new Value(*state->allocValue());
+            v->mkThunk(env, e);
+            addVarToScope(state->symbols.create(name), v);
+        } else {
+            Value v;
+            evalString(line, v);
+            printValue(std::cout, v, 1) << std::endl;
+        }
+    }
+
+    return true;
+}
+
+
+void NixRepl::loadFile(const Path & path)
+{
+    loadedFiles.remove(path);
+    loadedFiles.push_back(path);
+    Value v, v2;
+    state->evalFile(lookupFileArg(*state, path), v);
+    state->autoCallFunction(*autoArgs, v, v2);
+    addAttrsToScope(v2);
+}
+
+
+void NixRepl::initEnv()
+{
+    env = &state->allocEnv(envSize);
+    env->up = &state->baseEnv;
+    displ = 0;
+    staticEnv.vars.clear();
+
+    varNames.clear();
+    for (auto & i : state->staticBaseEnv.vars)
+        varNames.insert(i.first);
+}
+
+
+void NixRepl::reloadFiles()
+{
+    initEnv();
+
+    Strings old = loadedFiles;
+    loadedFiles.clear();
+
+    bool first = true;
+    for (auto & i : old) {
+        if (!first) std::cout << std::endl;
+        first = false;
+        std::cout << format("Loading '%1%'...") % i << std::endl;
+        loadFile(i);
+    }
+}
+
+
+void NixRepl::addAttrsToScope(Value & attrs)
+{
+    state->forceAttrs(attrs);
+    for (auto & i : *attrs.attrs)
+        addVarToScope(i.name, i.value);
+    std::cout << format("Added %1% variables.") % attrs.attrs->size() << std::endl;
+}
+
+
+void NixRepl::addVarToScope(const Symbol & name, Value * v)
+{
+    if (displ >= envSize)
+        throw Error("environment full; cannot add more variables");
+    staticEnv.vars[name] = displ;
+    env->values[displ++] = v;
+    varNames.insert((string) name);
+}
+
+
+Expr * NixRepl::parseString(string s)
+{
+    Expr * e = state->parseExprFromString(s, curDir, staticEnv);
+    return e;
+}
+
+
+void NixRepl::evalString(string s, Value & v)
+{
+    Expr * e = parseString(s);
+    e->eval(*state, *env, v);
+    state->forceValue(v);
+}
+
+
+std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int maxDepth)
+{
+    ValuesSeen seen;
+    return printValue(str, v, maxDepth, seen);
+}
+
+
+std::ostream & printStringValue(std::ostream & str, const char * string) {
+    str << "\"";
+    for (const char * i = string; *i; i++)
+        if (*i == '\"' || *i == '\\') str << "\\" << *i;
+        else if (*i == '\n') str << "\\n";
+        else if (*i == '\r') str << "\\r";
+        else if (*i == '\t') str << "\\t";
+        else str << *i;
+    str << "\"";
+    return str;
+}
+
+
+// FIXME: lot of cut&paste from Nix's eval.cc.
+std::ostream & NixRepl::printValue(std::ostream & str, Value & v, unsigned int maxDepth, ValuesSeen & seen)
+{
+    str.flush();
+    checkInterrupt();
+
+    state->forceValue(v);
+
+    switch (v.type()) {
+
+    case nInt:
+        str << ANSI_CYAN << v.integer << ANSI_NORMAL;
+        break;
+
+    case nBool:
+        str << ANSI_CYAN << (v.boolean ? "true" : "false") << ANSI_NORMAL;
+        break;
+
+    case nString:
+        str << ANSI_YELLOW;
+        printStringValue(str, v.string.s);
+        str << ANSI_NORMAL;
+        break;
+
+    case nPath:
+        str << ANSI_GREEN << v.path << ANSI_NORMAL; // !!! escaping?
+        break;
+
+    case nNull:
+        str << ANSI_CYAN "null" ANSI_NORMAL;
+        break;
+
+    case nAttrs: {
+        seen.insert(&v);
+
+        bool isDrv = state->isDerivation(v);
+
+        if (isDrv) {
+            str << "«derivation ";
+            Bindings::iterator i = v.attrs->find(state->sDrvPath);
+            PathSet context;
+            Path drvPath = i != v.attrs->end() ? state->coerceToPath(*i->pos, *i->value, context) : "???";
+            str << drvPath << "»";
+        }
+
+        else if (maxDepth > 0) {
+            str << "{ ";
+
+            typedef std::map<string, Value *> Sorted;
+            Sorted sorted;
+            for (auto & i : *v.attrs)
+                sorted[i.name] = i.value;
+
+            for (auto & i : sorted) {
+                if (isVarName(i.first))
+                    str << i.first;
+                else
+                    printStringValue(str, i.first.c_str());
+                str << " = ";
+                if (seen.find(i.second) != seen.end())
+                    str << "«repeated»";
+                else
+                    try {
+                        printValue(str, *i.second, maxDepth - 1, seen);
+                    } catch (AssertionError & e) {
+                        str << ANSI_RED "«error: " << e.msg() << "»" ANSI_NORMAL;
+                    }
+                str << "; ";
+            }
+
+            str << "}";
+        } else
+            str << "{ ... }";
+
+        break;
+    }
+
+    case nList:
+        seen.insert(&v);
+
+        str << "[ ";
+        if (maxDepth > 0)
+            for (unsigned int n = 0; n < v.listSize(); ++n) {
+                if (seen.find(v.listElems()[n]) != seen.end())
+                    str << "«repeated»";
+                else
+                    try {
+                        printValue(str, *v.listElems()[n], maxDepth - 1, seen);
+                    } catch (AssertionError & e) {
+                        str << ANSI_RED "«error: " << e.msg() << "»" ANSI_NORMAL;
+                    }
+                str << " ";
+            }
+        else
+            str << "... ";
+        str << "]";
+        break;
+
+    case nFunction:
+        if (v.isLambda()) {
+            std::ostringstream s;
+            s << v.lambda.fun->pos;
+            str << ANSI_BLUE "«lambda @ " << filterANSIEscapes(s.str()) << "»" ANSI_NORMAL;
+        } else if (v.isPrimOp()) {
+            str << ANSI_MAGENTA "«primop»" ANSI_NORMAL;
+        } else if (v.isPrimOpApp()) {
+            str << ANSI_BLUE "«primop-app»" ANSI_NORMAL;
+        } else {
+            abort();
+        }
+        break;
+
+    case nFloat:
+        str << v.fpoint;
+        break;
+
+    default:
+        str << ANSI_RED "«unknown»" ANSI_NORMAL;
+        break;
+    }
+
+    return str;
+}
+
+void runRepl(
+    ref<EvalState> evalState,
+    const std::map<std::string, Value *> & extraEnv)
+{
+    auto repl = std::make_unique<NixRepl>(evalState);
+
+    repl->initEnv();
+
+    std::set<std::string> names;
+
+    for (auto & [name, value] : extraEnv) {
+        names.insert(ANSI_BOLD + name + ANSI_NORMAL);
+        repl->addVarToScope(repl->state->symbols.create(name), value);
+    }
+
+    printError("The following extra variables are in scope: %s\n", concatStringsSep(", ", names));
+
+    repl->mainLoop({});
+}
+
+struct CmdRepl : StoreCommand, MixEvalArgs
+{
+    std::vector<std::string> files;
+
+    CmdRepl()
+    {
+        expectArgs({
+            .label = "files",
+            .handler = {&files},
+            .completer = completePath
+        });
+    }
+
+    std::string description() override
+    {
+        return "start an interactive environment for evaluating Nix expressions";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "repl.md"
+          ;
+    }
+
+    void run(ref<Store> store) override
+    {
+        evalSettings.pureEval = false;
+
+        auto evalState = make_ref<EvalState>(searchPath, store);
+
+        auto repl = std::make_unique<NixRepl>(evalState);
+        repl->autoArgs = getAutoArgs(*repl->state);
+        repl->mainLoop(files);
+    }
+};
+
+static auto rCmdRepl = registerCommand<CmdRepl>("repl");
+
+}