WIP

lib/#flake_env__versions.re#

@@ -0,0 +1,81 @@
+open Core;
+module Unix = Core_unix;
+
+module Util = Flake_env__util;
+
+
+type t = {
+  major: int,
+  minor: int,
+  point: int,
+};
+
+let init = (major, minor, point) => {
+  {major, minor, point}
+};
+
+let required_direnv_version = init(2, 21, 3);
+
+let required_nix_version = init(2, 10, 0);
+
+let semver_re = Re.compile(Re.Posix.re({|([0-9]+)\.([0-9]+)\.([0-9]+)|}));
+
+let compare = (a, b) => {
+  switch (a, b) {
+  | (a, b) when a.major == b.major && a.minor == b.minor && a.point == b.point => 0
+  | (a, b) when a.major < b.major => -1
+  | (a, b) when a.major == b.major && a.minor < b.minor => -1
+  | (a, b) when a.major == b.major && a.minor == b.minor && a.point < b.point => -1
+  | _ => 1
+  }
+}
+
+let extract_version_number = (cmd) => {
+  switch (Util.run_process(cmd, ["--version"])) {
+  | (Ok(), stdout)  when String.length(stdout) > 0 => {
+      let substrings = Re.exec(semver_re, stdout);
+      let groups = Re.Group.all(substrings);
+      if ((groups |> Array.length) == 4) {
+        Ok({
+          major: groups[1] |> int_of_string,
+          minor: groups[2] |> int_of_string,
+          point: groups[3] |> int_of_string
+        })
+      } else {
+        Error(Printf.sprintf("Stdout did not contain a version number for `%s --version`", cmd))
+      }
+    }
+    | _ => Error(Printf.sprintf("Failed executing '%s'\n", cmd))
+  }
+};
+
+let is_new_enough = (cur, needed) => {
+  switch (cur) {
+    | Ok(cur) => {
+        switch (compare(cur, needed)) {
+        | x when x < 0 => Ok(false)
+        | _ => Ok(true)
+        }
+      }
+    | Error(e) => Error(e)
+  }
+};
+
+let in_direnv = () => switch (Sys.getenv("direnv")) {
+    | Some(_) => true
+    | None => false
+};
+
+let preflight_versions = () => {
+  let is_nix_new_enough = is_new_enough(extract_version_number("nix"), required_nix_version);
+  let is_direnv_new_enough = is_new_enough(extract_version_number("direnv"), required_direnv_version);
+
+  switch (in_direnv(), is_direnv_new_enough, is_nix_new_enough) {
+    | (false, _, _) => Error("Not in direnv!")
+    | (_, Ok(false), _) => Error("Direnv version is not new enough")
+    | (_, _, Ok(false)) => Error("Nix version is not new enough")
+    | (_, Error(e), _) => Error(e)
+    | (_, _, Error(e)) => Error(e)
+    | (true, Ok(true), Ok(true)) => Ok()
+  }
+};

lib/dune

@@ -1,5 +1,14 @@
 (library
   (name lib)
   (public_name flake_env.lib)
-  (libraries core core_unix core_unix.filename_unix core_unix.sys_unix ppx_yojson_conv re sha)
+  (libraries
+    core
+    core_unix
+    core_unix.filename_unix
+    core_unix.sys_unix
+    fmt
+    ppx_yojson_conv
+    re
+    sha)
+  (instrumentation (backend bisect_ppx))
   (preprocess (pps ppx_yojson_conv ppx_jane ppx_inline_test)))

lib/flake_env__util.re

@@ -1,10 +1,55 @@
 open Core;
 module Unix = Core_unix;
 
-let nix = (args) => {
-  let stdout_chan = Unix.open_process_in(
-    "nix --extra-experimental-features \"nix-command flakes\" " ++ (args |> String.concat(~sep=" ")));
+let run_process = (name, args) => {
+  /*** Run a process [name] with args [args], returning (exit_code, stdout text) */
+  let stdout_chan = Unix.open_process_in(name ++ " " ++ (args |> String.concat(~sep=" ")));
   let stdout_content = stdout_chan |> In_channel.input_all;
   let exit_code = Unix.close_process_in(stdout_chan);
   (exit_code, stdout_content)
-}
+ };
+
+let nix = (args) => run_process("nix", ["--extra-experimental-features", "\"nix-command flakes\" ", ...args]);
+
+let hash_files = (filenames) => {
+  /*** Hash all entries in [filenames], returning a hex-encoded string of the hash of their contents */
+  let ctx = Sha1.init();
+  let () = filenames
+  |> Array.filter(~f=f => switch (Sys_unix.file_exists(f)) {
+      | `Yes => true
+      | _ => false
+    })
+  |> Array.iter(~f=(f) => {
+      f |> In_channel.create |> In_channel.input_all |> Sha1.update_string(ctx);
+    });
+  Sha1.finalize(ctx) |> Sha1.to_hex
+};
+
+let rec rmrf = (path) => {
+  switch (Unix.lstat(path).st_kind) {
+  | exception Unix.Unix_error(_, _, _) => ()
+  | S_REG => Unix.unlink(path)
+  | S_LNK => Unix.unlink(path)
+  | S_DIR => {
+      Sys_unix.readdir(path) |> Array.iter(~f=name => rmrf(Filename.concat(path, name)));
+      Unix.rmdir(path)
+    }
+  | S_CHR => Printf.eprintf("Don't know how to handle Character Device file\n")
+  | S_BLK => Printf.eprintf("Don't know how to handle Block Device file\n")
+  | S_FIFO => Printf.eprintf("Don't know how to handle FIFO file\n")
+  | S_SOCK => Printf.eprintf("Don't know how to handle Socket file\n")
+  }
+};
+
+let get_args = (argv) => {
+  switch (Array.length(argv)) {
+  | x when x >= 3 => {
+      let layout_directory = argv[1];
+      let flake_specifier = argv[2];
+      let other_args = snd(List.split_n(List.of_array(argv), 3));
+      Ok((layout_directory, flake_specifier, other_args))
+    }
+  | _ => Error()
+  }
+};
+

lib/flake_env__versions.re

@@ -1,28 +1,28 @@
 open Core;
 module Unix = Core_unix;
 
+module Util = Flake_env__util;
+
+
 type t = {
   major: int,
   minor: int,
   point: int,
 };
 
+let init = (major, minor, point) => {
+  {major, minor, point}
+};
+
+let required_direnv_version = init(2, 21, 3);
+
+let required_nix_version = init(2, 10, 0);
+
 let semver_re = Re.compile(Re.Posix.re({|([0-9]+)\.([0-9]+)\.([0-9]+)|}));
 
-let required_direnv_version = {
-  major: 2,
-  minor: 21,
-  point: 3
-};
+let pprint = (pp_fmt, version) => Fmt.pf(pp_fmt, "{ major: %d, minor: %d, point: %d }", version.major, version.minor, version.point);
 
-let required_nix_version = {
-  major: 2,
-  minor: 10,
-  point: 0
-};
-
-// TODO: test this
-let compare_version_number = (a, b) => {
+let compare = (a, b) => {
   switch (a, b) {
   | (a, b) when a.major == b.major && a.minor == b.minor && a.point == b.point => 0
   | (a, b) when a.major < b.major => -1
@@ -32,46 +32,47 @@ let compare_version_number = (a, b) => {
   }
 }
 
-let%test_unit "compare_version_number" = [%test_eq: int](compare_version_number({major: 1, minor: 0, point: 0}, {major: 2, minor: 0, point: 0}), -1);
-
 let extract_version_number = (cmd) => {
-  let full_cmd = cmd ++ " --version";
-  switch (Core_unix.open_process_in(full_cmd) |> In_channel.input_line) {
-  | Some(stdout) => {
+  switch (Util.run_process(cmd, ["--version"])) {
+  | (Ok(), stdout)  when String.length(stdout) > 0 => {
       let substrings = Re.exec(semver_re, stdout);
       let groups = Re.Group.all(substrings);
-      Ok({
-        major: groups[1] |> int_of_string,
-        minor: groups[2] |> int_of_string,
-        point: groups[3] |> int_of_string
-      })
+      if ((groups |> Array.length) == 4) {
+        Ok({
+          major: groups[1] |> int_of_string,
+          minor: groups[2] |> int_of_string,
+          point: groups[3] |> int_of_string
+        })
+      } else {
+        Error(Printf.sprintf("Stdout did not contain a version number for `%s --version`", cmd))
+      }
     }
-  | None => Error(Printf.sprintf("Failed executing '%s'\n", cmd))
+    | _ => Error(Printf.sprintf("Failed executing '%s'\n", cmd))
   }
 };
 
-let is_version_new_enough = (cur, needed) => {
+let is_new_enough = (cur, needed) => {
   switch (cur) {
     | Ok(cur) => {
-        switch (compare_version_number(cur, needed)) {
+        switch (compare(cur, needed)) {
         | x when x < 0 => Ok(false)
         | _ => Ok(true)
         }
       }
     | Error(e) => Error(e)
   }
-}
+};
 
-let preflight_versions = () => {
-  let in_direnv = switch (Sys.getenv("direnv")) {
+let in_direnv = () => switch (Sys.getenv("direnv")) {
     | Some(_) => true
     | None => false
-  };
+};
 
-  let is_nix_new_enough = is_version_new_enough(extract_version_number("nix"), required_nix_version);
-  let is_direnv_new_enough = is_version_new_enough(extract_version_number("direnv"), required_direnv_version);
+let preflight_versions = () => {
+  let is_nix_new_enough = is_new_enough(extract_version_number("nix"), required_nix_version);
+  let is_direnv_new_enough = is_new_enough(extract_version_number("direnv"), required_direnv_version);
 
-  switch (in_direnv, is_direnv_new_enough, is_nix_new_enough) {
+  switch (in_direnv(), is_direnv_new_enough, is_nix_new_enough) {
     | (false, _, _) => Error("Not in direnv!")
     | (_, Ok(false), _) => Error("Direnv version is not new enough")
     | (_, _, Ok(false)) => Error("Nix version is not new enough")

lib/lib.re

@@ -1,3 +1,73 @@
+open Core;
+module Unix = Core_unix;
+
 module Util = Flake_env__util;
 module Watches = Flake_env__watches;
 module Versions = Flake_env__versions;
+
+let print_cur_cache = (profile_rc) => {
+  In_channel.read_all(profile_rc) |> Printf.printf("%s")
+};
+
+let clean_old_gcroots = (layout_dir) => {
+  Util.rmrf(layout_dir ++ "/flake-inputs/");
+  Util.rmrf(layout_dir);
+  Unix.mkdir_p(layout_dir ++ "/flake-inputs/");
+};
+
+let add_gcroot = (store_path, symlink) => {
+  switch (Util.nix(["build", "--out-link", symlink, store_path])) {
+  | (Ok(), _) => Ok()
+  | (err, _) => err
+  }
+};
+
+let freshen_cache = (layout_dir, hash, flake_specifier, other_args) => {
+    clean_old_gcroots(layout_dir);
+    let tmp_profile = layout_dir ++ "flake-tmp-profile."  ++ Core.Pid.to_string(Core_unix.getpid());
+
+    let pde_args = ["print-dev-env", "--profile", tmp_profile, flake_specifier, ...other_args];
+    let (exit_code, stdout_content) = Util.nix(pde_args);
+
+    let profile = layout_dir ++ "/flake-profile-" ++ hash;
+    let profile_rc = profile ++ ".rc";
+
+    switch (exit_code) {
+    | Ok() => {
+        Out_channel.with_file(~f=f=> Out_channel.output_string(f, stdout_content), profile_rc);
+        switch (add_gcroot(tmp_profile, profile)) {
+        | Ok() => {
+            Sys_unix.remove(tmp_profile);
+            let flake_input_cache_path = layout_dir ++ "/flake-inputs/"
+              let flake_inputs = Watches.get_input_paths();
+            flake_inputs |> List.iter(~f=(inpt) => {
+                switch (add_gcroot("/nix/store/" ++ inpt, flake_input_cache_path ++ inpt)) {
+                | Ok() => ()
+                | err => Printf.eprintf("Failed creating flake-input gcroot: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
+                };
+              });
+            print_cur_cache(profile_rc);
+          }
+        | err => {
+            Printf.eprintf("Failed creating gcroot: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
+            exit(1);
+          }
+        };
+      }
+    | err => {
+        Printf.eprintf("Failed evaluating flake: %s\n", Core_unix.Exit_or_signal.to_string_hum(err));
+        exit(1);
+      }
+    };
+  };
+
+let preflight = (layout_directory) => {
+  switch (Versions.preflight_versions(), Sys_unix.is_directory(layout_directory)) {
+  | (Ok(_), `Yes) => Ok()
+  | (Ok(_), _) => {
+      Unix.mkdir_p(layout_directory);
+      Ok()
+    }
+  | (err, _) => err
+  }
+}