Aliases and multishell support (#30)

* Use variants instead of a boolean

* Add infrastructure for multishell and aliases: Aliases are required because I want to have a default node version on startup

* create alias command

* fmt

* Added aliases (Fixes #29) and opt-in multishell support (Fixes #19)

* Better docs

* update snapshot

* Some/Fail => Some/None

* add lint-staged

* use refmt and all of prettier are grouped

* System.readdir => Fs.readdir (now uses Lwt)

* use lstat for file_exists: check if symlink exists instead of actual linked file. also, initialize the Random seed on Env

* Remove fish set options that were added in trial and error

* Bootstrap script

* add bootstrap documentation

.ci/bootstrap

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+GIT_ROOT=$(git rev-parse --show-toplevel)
+
+if [ "$GIT_ROOT" == "" ]; then
+  echo "Git root cannot be empty"
+  exit 1
+fi
+
+rm -f $GIT_ROOT/.git/hooks/pre-commit &> /dev/null
+ln -s $GIT_ROOT/.ci/pre-commit-hook $GIT_ROOT/.git/hooks/pre-commit

.ci/pre-commit-hook

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+set -e
+
+npx lint-staged

README.md

@@ -11,6 +11,7 @@
 </div>
 
 ## Features
+
 :sparkles: Single file, easy installation
 
 :rocket: Built with speed in mind
@@ -29,9 +30,9 @@ curl https://raw.githubusercontent.com/Schniz/fnm/master/.ci/install.sh | bash
 
 ### Manually
 
-* Download the [latest release binary](https://github.com/Schniz/fnm/releases) for your system
+- Download the [latest release binary](https://github.com/Schniz/fnm/releases) for your system
-* Make it available globally on `$PATH`
+- Make it available globally on `$PATH`
-* Add the following line to your `.bashrc`/`.zshrc` file:
+- Add the following line to your `.bashrc`/`.zshrc` file:
 
   ```bash
   eval `fnm env`
@@ -63,11 +64,15 @@ Lists the installed Node versions.
 
 Lists the Node versions available to download remotely.
 
-### `fnm env [--fish]`
+### `fnm env [--multi] [--fish]`
+
+Prints the required shell commands in order to configure your shell, Bash compliant by default.
 
-Prints the required shell commands in order to configure your shell, Bash compliant by default. Provide `--fish` to output the Fish-compliant version.
+- Providing `--multi` will output the multishell support, allowing a different current Node version per shell
+- Providing `--fish` will output the Fish-compliant version.
 
 ## Future Plans
+
 - [ ] Feature: make versions complete the latest: `10` would infer the latest minor and patch versions of node 10. `10.1` would infer the latest patch version of node 10.1
 - [ ] Feature: `fnm use --install`, `fnm use --quiet`
 - [ ] Feature: `fnm install lts`?
@@ -88,6 +93,7 @@ PRs welcome :tada:
 npm install -g esy
 git clone https://github.com/Schniz/fnm.git
 esy install
+esy bootstrap
 esy build
 ```
 

esy.lock/opam/ppxlib.0.5.0/opam

@@ -15,12 +15,12 @@ run-test: [
 ]
 depends: [
   "ocaml"                   {>= "4.04.1"}
-  "base"                    {>= "v0.11.0"}
+  "base"                    {>= "v0.11.0" & < "v0.12"}
   "dune"                    {build}
   "ocaml-compiler-libs"     {>= "v0.11.0"}
   "ocaml-migrate-parsetree" {>= "1.0.9"}
   "ppx_derivers"            {>= "1.0"}
-  "stdio"                   {>= "v0.11.0"}
+  "stdio"                   {>= "v0.11.0" & < "v0.12"}
   "ocamlfind"               {with-test}
 ]
 synopsis: "Base library and tools for ppx rewriters"

esy.lock/opam/uutf.1.0.2/opam

@@ -20,8 +20,9 @@ build: [[
   "ocaml" "pkg/pkg.ml" "build"
           "--pinned" "%{pinned}%"
           "--with-cmdliner" "%{cmdliner:installed}%" ]]
-synopsis: "Non-blocking streaming Unicode codec for OCaml"
+synopsis: """Non-blocking streaming Unicode codec for OCaml"""
-description: """
+description: """\
+
 Uutf is a non-blocking streaming codec to decode and encode the UTF-8,
 UTF-16, UTF-16LE and UTF-16BE encoding schemes. It can efficiently
 work character by character without blocking on IO. Decoders perform
@@ -31,8 +32,9 @@ Functions are also provided to fold over the characters of UTF encoded
 OCaml string values and to directly encode characters in OCaml
 Buffer.t values.
 
-Uutf has no dependency and is distributed under the ISC license."""
+Uutf has no dependency and is distributed under the ISC license.
+"""
 url {
-  src: "http://erratique.ch/software/uutf/releases/uutf-1.0.1.tbz"
+archive: "http://erratique.ch/software/uutf/releases/uutf-1.0.2.tbz"
-  checksum: "md5=b8535f974027357094c5cdb4bf03a21b"
+checksum: "a7c542405a39630c689a82bd7ef2292c"
 }

esy.lock/opam/yojson.1.6.0/opam

@@ -9,12 +9,14 @@ build: [
   ["dune" "subst"] {pinned}
   ["dune" "build" "-p" name "-j" jobs]
 ]
+run-test: [["dune" "runtest" "-p" name "-j" jobs]]
 depends: [
   "ocaml" {>= "4.02.3"}
   "dune" {build}
   "cppo" {build}
   "easy-format"
   "biniou" {>= "1.2.0"}
+  "alcotest" {with-test & >= "0.8.5"}
 ]
 synopsis:
   "Yojson is an optimized parsing and printing library for the JSON format"
@@ -31,6 +33,6 @@ The program atdgen can be used to derive OCaml-JSON serializers and
 deserializers from type definitions."""
 url {
   src:
-    "https://github.com/ocaml-community/yojson/releases/download/1.5.0/yojson-1.5.0.tbz"
+    "https://github.com/ocaml-community/yojson/releases/download/1.6.0/yojson-1.6.0.tbz"
-  checksum: "md5=d80de1bacdde292af42f7c78b323da7b"
+  checksum: "md5=8ca16557d3068253cc375452af3bde96"
 }

executable/Alias.re

@@ -0,0 +1,30 @@
+open Fnm;
+
+let run = (~name, ~version) => {
+  let version = Versions.format(version);
+  let versionPath = Filename.concat(Directories.nodeVersions, version);
+  let%lwt versionInstalled = Lwt_unix.file_exists(versionPath);
+
+  if (!versionInstalled) {
+    Console.error(
+      <Pastel color=Pastel.Red>
+        "Can't find a version installed in "
+        versionPath
+      </Pastel>,
+    );
+    exit(1);
+  };
+
+  Console.log(
+    <Pastel>
+      "Aliasing "
+      <Pastel color=Pastel.Cyan> name </Pastel>
+      " to "
+      <Pastel color=Pastel.Cyan> version </Pastel>
+    </Pastel>,
+  );
+
+  let%lwt () = Versions.Aliases.set(~alias=name, ~versionPath);
+
+  Lwt.return();
+};

executable/Env.re

@@ -1,14 +1,50 @@
 open Fnm;
 
-let run = isFishShell => {
+let symlinkExists = path => {
-  if (isFishShell) {
+  try%lwt (Lwt_unix.lstat(path) |> Lwt.map(_ => true)) {
-    Console.log(
+  | _ => Lwt.return(false)
-      Printf.sprintf("set PATH %s/bin $PATH", Directories.currentVersion),
+  };
+};
+
+let rec makeTemporarySymlink = () => {
+  let suggestedName =
+    Filename.concat(
+      Filename.get_temp_dir_name(),
+      "fnm-shell-"
+      ++ (Random.int32(9999999 |> Int32.of_int) |> Int32.to_string),
     );
+
+  let%lwt exists = symlinkExists(suggestedName);
+
+  if (exists) {
+    let%lwt suggestedName = makeTemporarySymlink();
+    Lwt.return(suggestedName);
   } else {
-    Console.log(
+    let%lwt _ =
-      Printf.sprintf("export PATH=%s/bin:$PATH", Directories.currentVersion),
+      Lwt_unix.symlink(
+        Filename.concat(Directories.defaultVersion, "installation"),
+        suggestedName,
       );
+    Lwt.return(suggestedName);
+  };
+};
+
+let run = (~shell, ~multishell) => {
+  open Lwt;
+
+  Random.self_init();
+
+  let%lwt path =
+    multishell
+      ? makeTemporarySymlink() : Lwt.return(Directories.globalCurrentVersion);
+
+  switch (shell) {
+  | System.Shell.Bash =>
+    Printf.sprintf("export PATH=%s/bin:$PATH", path) |> Console.log;
+    Printf.sprintf("export FNM_MULTISHELL_PATH=%s", path) |> Console.log;
+  | System.Shell.Fish =>
+    Printf.sprintf("set PATH %s/bin $PATH;", path) |> Console.log;
+    Printf.sprintf("set FNM_MULTISHELL_PATH %s;", path) |> Console.log;
   };
 
   Lwt.return();

executable/FnmApp.re

@@ -1,11 +1,18 @@
 let version = Fnm.Fnm__Package.version;
 
 module Commands = {
-  let use = version => Lwt_main.run(Use.run(version));
+  let use = (version, quiet) => Lwt_main.run(Use.run(~version, ~quiet));
+  let alias = (version, name) => Lwt_main.run(Alias.run(~name, ~version));
   let listRemote = () => Lwt_main.run(ListRemote.run());
   let listLocal = () => Lwt_main.run(ListLocal.run());
   let install = version => Lwt_main.run(Install.run(~version));
-  let env = isFishShell => Lwt_main.run(Env.run(isFishShell));
+  let env = (isFishShell, isMultishell) =>
+    Lwt_main.run(
+      Env.run(
+        ~shell=Fnm.System.Shell.(isFishShell ? Fish : Bash),
+        ~multishell=isMultishell,
+      ),
+    );
 };
 
 open Cmdliner;
@@ -71,6 +78,11 @@ let use = {
   let doc = "Switch to another installed node version";
   let man = [];
 
+  let quiet = {
+    let doc = "Don't print stuff";
+    Arg.(value & flag & info(["quiet"], ~doc));
+  };
+
   let selectedVersion = {
     let doc = "Switch to version $(docv).\nLeave empty to look for value from `.nvmrc`";
     Arg.(
@@ -79,11 +91,45 @@ let use = {
   };
 
   (
-    Term.(const(Commands.use) $ selectedVersion),
+    Term.(const(Commands.use) $ selectedVersion $ quiet),
     Term.info("use", ~version, ~doc, ~exits=Term.default_exits, ~man),
   );
 };
 
+let alias = {
+  let doc = "Alias a version";
+  let sdocs = Manpage.s_common_options;
+  let man = help_secs;
+
+  let selectedVersion = {
+    let doc = "The version to be aliased";
+    Arg.(
+      required
+      & pos(0, some(string), None)
+      & info([], ~docv="VERSION", ~doc)
+    );
+  };
+
+  let aliasName = {
+    let doc = "The alias name";
+    Arg.(
+      required & pos(1, some(string), None) & info([], ~docv="NAME", ~doc)
+    );
+  };
+
+  (
+    Term.(const(Commands.alias) $ selectedVersion $ aliasName),
+    Term.info(
+      "alias",
+      ~version,
+      ~doc,
+      ~exits=Term.default_exits,
+      ~man,
+      ~sdocs,
+    ),
+  );
+};
+
 let env = {
   let doc = "Show env configurations";
   let sdocs = Manpage.s_common_options;
@@ -94,8 +140,13 @@ let env = {
     Arg.(value & flag & info(["fish"], ~doc));
   };
 
+  let isMultishell = {
+    let doc = "Allow different Node versions for each shell";
+    Arg.(value & flag & info(["multi"], ~doc));
+  };
+
   (
-    Term.(const(Commands.env) $ isFishShell),
+    Term.(const(Commands.env) $ isFishShell $ isMultishell),
     Term.info("env", ~version, ~doc, ~exits=Term.default_exits, ~man, ~sdocs),
   );
 };
@@ -119,5 +170,8 @@ let defaultCmd = {
 };
 
 let _ =
-  Term.eval_choice(defaultCmd, [install, use, listLocal, listRemote, env])
+  Term.eval_choice(
+    defaultCmd,
+    [install, use, alias, listLocal, listRemote, env],
+  )
   |> Term.exit;

executable/ListLocal.re

@@ -6,22 +6,29 @@ let main = () =>
   Versions.Local.(
     {
       let%lwt versions =
-        Versions.getInstalledVersions()
+        try%lwt (Versions.getInstalledVersions()) {
-        |> Result.mapError(_ => Cant_read_local_versions)
+        | _ => Lwt.fail(Cant_read_local_versions)
-        |> Result.toLwtErr;
+        };
       let currentVersion = Versions.getCurrentVersion();
 
       Console.log("The following versions are installed:");
 
       versions
-      |> Array.iter(version => {
+      |> List.iter(version => {
            let color =
              switch (currentVersion) {
              | None => None
              | Some(x) when x.name == version.name => Some(Pastel.Cyan)
              | Some(_) => None
              };
-           Console.log(<Pastel ?color> "* " {version.name} </Pastel>);
+           let aliases =
+             List.length(version.aliases) === 0
+               ? ""
+               : Printf.sprintf(
+                   " (%s)",
+                   version.aliases |> String.concat(", "),
+                 );
+           Console.log(<Pastel ?color> "* " {version.name} aliases </Pastel>);
          });
 
       Lwt.return();

executable/Use.re

@@ -4,18 +4,27 @@ let lwtIgnore = lwt => Lwt.catch(() => lwt, _ => Lwt.return());
 
 exception Version_Not_Installed(string);
 
-let switchVersion = version => {
+let log = (~quiet, arg) =>
-  let versionDir = Filename.concat(Directories.nodeVersions, version);
+  if (!quiet) {
+    Console.log(arg);
+  };
 
-  let%lwt _ =
+let switchVersion = (~version, ~quiet) => {
-    if%lwt (Lwt_unix.file_exists(versionDir) |> Lwt.map(x => !x)) {
+  open Lwt;
-      Lwt.fail(Version_Not_Installed(version));
+  let log = log(~quiet);
+  let%lwt parsedVersion =
+    Versions.parse(version) >>= Opt.toLwt(Version_Not_Installed(version));
+
+  let%lwt versionPath =
+    switch (parsedVersion) {
+    | Local(version) => Versions.Local.toDirectory(version) |> Lwt.return
+    | Alias(alias) => Versions.Aliases.toDirectory(alias) |> Lwt.return
     };
 
-  let destination = Filename.concat(versionDir, "installation");
+  let destination = Filename.concat(versionPath, "installation");
   let source = Directories.currentVersion;
 
-  Console.log(
+  log(
     <Pastel>
       "Linking "
       <Pastel color=Pastel.Cyan> source </Pastel>
@@ -25,28 +34,37 @@ let switchVersion = version => {
   );
 
   let%lwt _ = Lwt_unix.unlink(Directories.currentVersion) |> lwtIgnore;
-  let%lwt _ = Lwt_unix.symlink(destination, Directories.currentVersion);
+  let%lwt _ = Lwt_unix.symlink(destination, Directories.currentVersion)
+  and defaultAliasExists = Lwt_unix.file_exists(Directories.defaultVersion);
+
+  let%lwt _ =
+    if (!defaultAliasExists) {
+      Versions.Aliases.set(~alias="default", ~versionPath=destination);
+    } else {
+      Lwt.return();
+    };
 
-  Console.log(
+  log(
     <Pastel> "Using " <Pastel color=Pastel.Cyan> version </Pastel> </Pastel>,
   );
 
   Lwt.return();
 };
 
-let main = (~version as providedVersion) => {
+let main = (~version as providedVersion, ~quiet) => {
   let%lwt version =
     switch (providedVersion) {
     | Some(version) => Lwt.return(version)
     | None => Nvmrc.getVersion()
     };
-  switchVersion(Versions.format(version));
+  switchVersion(~version, ~quiet);
 };
 
-let run = version =>
+let run = (~version, ~quiet) =>
-  try%lwt (main(~version)) {
+  try%lwt (main(~version, ~quiet)) {
   | Version_Not_Installed(version) =>
-    Console.log(
+    log(
+      ~quiet,
       <Pastel color=Pastel.Red>
         "The following version is not installed: "
         version
@@ -54,7 +72,8 @@ let run = version =>
     )
     |> Lwt.return
   | Nvmrc.Version_Not_Provided =>
-    Console.log(
+    log(
+      ~quiet,
       <Pastel color=Pastel.Red>
         "No .nvmrc was found in the current directory. Please provide a version number."
       </Pastel>,

feature_tests/fish/run.fish

@@ -1,6 +1,7 @@
 #!/usr/bin/env fish
 
 eval (fnm env --fish)
+
 fnm install v8.11.3
 fnm use v8.11.3
 

feature_tests/multishell/run.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+set -e
+
+eval $(fnm env)
+
+fnm install v8.11.3
+fnm install v11.9.0
+
+fnm use v8.11.3
+
+bash -c '
+  set -e
+  eval $(fnm env --multi)
+  fnm use v11.9.0
+  echo "> verifying version v11.9.0 for child bash"
+  if [ "$(node -v)" == "v11.9.0" ]; then
+    echo "Okay!"
+  else
+    echo "Node version should be v11.9.0 in the bash fork"
+    exit 1
+  fi
+'
+
+echo "> verifying version v8.11.3 for parent bash"
+if [ "$(node -v)" == "v8.11.3" ]; then
+  echo "Okay!"
+else
+  echo "Node version should be v8.11.3 in the base bash"
+  exit 1
+fi

library/Compression.re

@@ -6,8 +6,8 @@ let extractFile = (~into as destination, filepath) => {
       ~args=[|"-xvf", filepath, "--directory", destination|],
       ~stderr=`Dev_null,
     );
-  let%lwt files = Fs.readdir(destination) |> Result.toLwt;
+  let%lwt files = Fs.readdir(destination);
-  let filename = files[0];
+  let filename = List.hd(files);
   Lwt_unix.rename(
     Filename.concat(destination, filename),
     Filename.concat(destination, "installation"),

library/Directories.re

@@ -9,5 +9,9 @@ let sfwRoot =
     }
   );
 let nodeVersions = Filename.concat(sfwRoot, "node-versions");
-let currentVersion = Filename.concat(sfwRoot, "current");
+let globalCurrentVersion = Filename.concat(sfwRoot, "current");
+let currentVersion =
+  Opt.(Sys.getenv_opt("FNM_MULTISHELL_PATH") or globalCurrentVersion);
 let downloads = Filename.concat(sfwRoot, "downloads");
+let aliases = Filename.concat(sfwRoot, "aliases");
+let defaultVersion = Filename.concat(aliases, "default");

library/Fs.re

@@ -1,11 +1,30 @@
 open Core;
 
-let readdir = dir =>
+let readdir = dir => {
-  switch (Sys.readdir(dir)) {
+  let items = ref([]);
-  | x => Ok(x)
+  let%lwt dir = Lwt_unix.opendir(dir);
-  | exception (Sys_error(error)) => Error(error)
+  let iterate = () => {
+    let%lwt _ =
+      while%lwt (true) {
+        let%lwt value = Lwt_unix.readdir(dir);
+        if (value.[0] != '.') {
+          items := [value, ...items^];
+        };
+        Lwt.return();
+      };
+
+    Lwt.return([]);
   };
 
+  let%lwt items =
+    try%lwt (iterate()) {
+    | End_of_file => Lwt.return(items^)
+    };
+
+  let%lwt _ = Lwt_unix.closedir(dir);
+  Lwt.return(items);
+};
+
 let writeFile = (path, contents) => {
   let%lwt x = Lwt_unix.openfile(path, [Unix.O_RDWR, Unix.O_CREAT], 777);
   let%lwt _ =

library/Http.re

@@ -14,7 +14,7 @@ let rec getBody = listOfStrings => {
   };
 };
 
-let rec getStatus = string => {
+let getStatus = string => {
   List.nth(String.split_on_char(' ', string), 1);
 };
 
@@ -27,7 +27,7 @@ let verifyStatus = response => {
   | 200 => Lwt.return(response)
   | x when x / 100 == 4 => Lwt.fail(Not_found(response))
   | x when x / 100 == 5 => Lwt.fail(Internal_server_error(response))
-  | x => Lwt.fail(Unknown_status_code(response))
+  | _ => Lwt.fail(Unknown_status_code(response))
   };
 };
 

library/Opt.re

@@ -28,6 +28,12 @@ let toResult = (error, opt) =>
   | Some(x) => Ok(x)
   };
 
+let toLwt = (error, opt) =>
+  switch (opt) {
+  | Some(x) => Lwt.return(x)
+  | None => Lwt.fail(error)
+  };
+
 let some = x => Some(x);
 
 let (or) = (opt, b) => fold(() => b, x => x, opt);

library/System.re

@@ -8,6 +8,12 @@ let unix_exec =
 let mkdirp = destination =>
   unix_exec("mkdir", ~stderr=`Dev_null, ~args=[|"-p", destination|]);
 
+module Shell = {
+  type t =
+    | Bash
+    | Fish;
+};
+
 module NodeArch = {
   type t =
     | X32

library/Versions.re

@@ -1,15 +1,74 @@
 module VersionSet = Set.Make(String);
 
+let lwtIgnore = lwt => Lwt.catch(() => lwt, _ => Lwt.return());
+
 module Local = {
   type t = {
     name: string,
     fullPath: string,
+    aliases: list(string),
   };
+
+  let toDirectory = name => Filename.concat(Directories.nodeVersions, name);
 };
 
 exception Version_not_found(string);
 exception Already_installed(string);
 
+module Aliases = {
+  module VersionAliasMap = Map.Make(String);
+
+  type t = {
+    name: string,
+    versionName: string,
+    fullPath: string,
+  };
+
+  let toDirectory = name => Filename.concat(Directories.aliases, name);
+
+  let getAll = () => {
+    let%lwt aliases = Fs.readdir(Directories.aliases);
+    aliases
+    |> List.map(alias => {
+         let fullPath = Filename.concat(Directories.aliases, alias);
+         {
+           name: alias,
+           fullPath,
+           versionName:
+             Filename.concat(Directories.aliases, alias)
+             |> Fs.realpath
+             |> Filename.basename,
+         };
+       })
+    |> Lwt.return;
+  };
+
+  let byVersion = () => {
+    let%lwt aliases = getAll();
+    aliases
+    |> List.fold_left(
+         (map, curr) => {
+           let value =
+             switch (VersionAliasMap.find_opt(curr.versionName, map)) {
+             | None => [curr.name]
+             | Some(arr) => [curr.name, ...arr]
+             };
+           VersionAliasMap.add(curr.versionName, value, map);
+         },
+         VersionAliasMap.empty,
+       )
+    |> Lwt.return;
+  };
+
+  let set = (~alias, ~versionPath) => {
+    let aliasPath = alias |> toDirectory;
+    let%lwt _ = System.mkdirp(Directories.aliases);
+    let%lwt _ = Lwt_unix.unlink(aliasPath) |> lwtIgnore;
+    let%lwt _ = Lwt_unix.symlink(versionPath, aliasPath);
+    Lwt.return();
+  };
+};
+
 module Remote = {
   type t = {
     name: string,
@@ -30,11 +89,12 @@ module Remote = {
     };
 
   let getInstalledVersionSet = () =>
-    Fs.readdir(Directories.nodeVersions)
+    Lwt.(
-    |> Result.fold(_ => [||], x => x)
+      catch(() => Fs.readdir(Directories.nodeVersions), _ => return([]))
-    |> Array.fold_left(
+      >|= List.fold_left(
             (acc, curr) => VersionSet.add(curr, acc),
             VersionSet.empty,
+          )
     );
 
   let getRelativeLinksFromHTML = html =>
@@ -105,23 +165,30 @@ let getCurrentVersion = () =>
   switch (Fs.realpath(Directories.currentVersion)) {
   | installationPath =>
     let fullPath = Filename.dirname(installationPath);
-    Some(Local.{fullPath, name: Core.Filename.basename(fullPath)});
+    Some(
+      Local.{fullPath, name: Core.Filename.basename(fullPath), aliases: []},
+    );
   | exception (Unix.Unix_error(_, _, _)) => None
   };
 
 let getInstalledVersions = () =>
-  Fs.readdir(Directories.nodeVersions)
+  Lwt.(
-  |> Result.map(x => {
+    {
-       Array.sort(Remote.compare, x);
+      let%lwt versions =
-       x;
+        Fs.readdir(Directories.nodeVersions) >|= List.sort(Remote.compare)
-     })
+      and aliases = Aliases.byVersion();
-  |> Result.map(
+
-       Array.map(name =>
+      versions
+      |> List.map(name =>
            Local.{
              name,
              fullPath: Filename.concat(Directories.nodeVersions, name),
+             aliases:
+               Opt.(Aliases.VersionAliasMap.find_opt(name, aliases) or []),
+           }
+         )
+      |> Lwt.return;
     }
-       ),
   );
 
 let getRemoteVersions = () => {
@@ -129,7 +196,7 @@ let getRemoteVersions = () => {
     Http.makeRequest("https://nodejs.org/dist/") |> Lwt.map(Http.body);
 
   let versions = bodyString |> Remote.getRelativeLinksFromHTML;
-  let installedVersions = Remote.getInstalledVersionSet();
+  let%lwt installedVersions = Remote.getInstalledVersionSet();
 
   versions
   |> Core.List.filter(~f=x =>
@@ -147,14 +214,35 @@ let getRemoteVersions = () => {
   |> Lwt.return;
 };
 
+type t =
+  | Alias(string)
+  | Local(string);
+
+let parse = version => {
+  let formattedVersion = format(version);
+  let aliasPath = Aliases.toDirectory(version);
+  let versionPath = Local.toDirectory(formattedVersion);
+
+  let%lwt aliasExists = Lwt_unix.file_exists(aliasPath)
+  and versionExists = Lwt_unix.file_exists(versionPath);
+
+  switch (versionExists, aliasExists) {
+  | (true, _) => Some(Local(formattedVersion)) |> Lwt.return
+  | (_, true) => Some(Alias(version)) |> Lwt.return
+  | (false, false) => Lwt.return_none
+  };
+};
+
 let throwIfInstalled = versionName => {
-  getInstalledVersions()
+  let%lwt installedVersions =
-  |> Result.fold(
+    try%lwt (getInstalledVersions()) {
-       _ => Lwt.return(),
+    | _ => Lwt.return([])
-       xs =>
+    };
-         Array.exists(x => Local.(x.name == versionName), xs)
+  let isAlreadyInstalled =
-         |> (
+    installedVersions |> List.exists(x => Local.(x.name == versionName));
-           x => x ? Lwt.fail(Already_installed(versionName)) : Lwt.return()
+  if (isAlreadyInstalled) {
-         ),
+    Lwt.fail(Already_installed(versionName));
-     );
+  } else {
+    Lwt.return();
+  };
 };

package.json

@@ -13,20 +13,50 @@
   },
   "buildDirs": {
     "test": {
-      "require": ["fnm.lib", "rely.lib"],
+      "require": [
+        "fnm.lib",
+        "rely.lib"
+      ],
       "main": "TestFnm",
       "name": "TestFnm.exe",
-      "ocamloptFlags": ["-linkall", "-g"]
+      "ocamloptFlags": [
+        "-linkall",
+        "-g"
+      ]
     },
     "library": {
-      "preprocess": ["pps", "lwt_ppx", "ppx_let"],
+      "preprocess": [
-      "require": ["str", "core", "lwt", "lwt.unix", "lambdasoup", "semver"],
+        "pps",
+        "lwt_ppx",
+        "ppx_let"
+      ],
+      "require": [
+        "str",
+        "core",
+        "lwt",
+        "lwt.unix",
+        "lambdasoup",
+        "semver"
+      ],
       "name": "fnm.lib",
       "namespace": "Fnm"
     },
     "executable": {
-      "preprocess": ["pps", "lwt_ppx", "ppx_let"],
+      "preprocess": [
-      "require": ["core", "cmdliner", "lwt", "lwt.unix", "lambdasoup", "console.lib", "pastel.lib", "fnm.lib"],
+        "pps",
+        "lwt_ppx",
+        "ppx_let"
+      ],
+      "require": [
+        "core",
+        "cmdliner",
+        "lwt",
+        "lwt.unix",
+        "lambdasoup",
+        "console.lib",
+        "pastel.lib",
+        "fnm.lib"
+      ],
       "main": "FnmApp",
       "name": "fnm.exe"
     }
@@ -35,6 +65,7 @@
     "pesy": "bash -c 'env PESY_MODE=update pesy'",
     "update-fnm-package": "node ./.ci/prepare-fnm-package.js",
     "verify-fnm-package": "node ./.ci/prepare-fnm-package.js --fail-on-difference",
+    "bootstrap": ".ci/bootstrap",
     "test": "esy x TestFnm.exe",
     "fmt": "bash -c 'refmt --in-place {library,executable,test}/*.re'"
   },
@@ -59,6 +90,20 @@
   "devDependencies": {
     "@opam/merlin": "*",
     "prettier": "*",
-    "jest-diff": "24.0.0"
+    "jest-diff": "24.0.0",
+    "lint-staged": "*"
+  },
+  "lint-staged": {
+    "*.re": [
+      "esy refmt --in-place",
+      "git add"
+    ],
+    "*.{js,md,json}": [
+      "esy prettier --write",
+      "git add"
+    ],
+    "package.json": [
+      "esy verify-fnm-package"
+    ]
   }
 }

test/__snapshots__/Smoke_test.4d362c3c.0.snapshot

@@ -1,3 +1,4 @@
 Smoke test › env
 export PATH=<sfwRoot>/current/bin:$PATH
+export FNM_MULTISHELL_PATH=<sfwRoot>/current