refactor(nu_conda): improve performance and compatibility

modules/virtual_environments/nu_conda/README.md

@@ -1,9 +1,11 @@
 # Conda Module for Nushell
-A simple module for activating and deactivating Conda environments.
+A simple module for finding, listing, activating, and deactivating Conda environments.
 
 
 ## Prerequisites
-- [nushell](https://github.com/nushell/nushell) >= 0.94.0
+The following commands must be available in your version of Nushell:
+- [job](https://www.nushell.sh/commands/docs/job.html)
+- [std-rfc/kv](https://github.com/nushell/nushell/blob/main/crates/nu-std/std-rfc/kv/mod.nu)
 
 
 ## Installation
@@ -12,16 +14,18 @@ Put `nu_conda.nu` into the module folder of your nushell configuration workspace
 
 ## Usage
 ```nu
-use nu_conda.nu         # activate module
-nu_conda activate py36  # activate a Conda environment, e.g. py36
-nu_conda deactivate     # deactivate the activated Conda environment
-nu_conda list           # list available environments, same as `$env.CONDA_ENVS`
+use nu_conda.nu          # import module, Conda environments will be searched
+nu_conda activate py310  # activate a Conda environment, e.g. py310
+nu_conda deactivate      # deactivate the activated Conda environment
+nu_conda find            # find/update available environments
+nu_conda list            # list available environments, same as `$env.CONDA_ENVS`
 ```
 
 ## How It Works
-This module re-implements the activation and deactivation functionalities of
-the [conda.nu](https://github.com/Neur1n/nu_scripts/blob/main/virtual_environments/conda.nu)
-module while providing a better performance, but not fully replacing it.
+> [!NOTE]
+> Originally, this module cached Conda environment information during import,
+> which increased startup time. It now performs the caching in a background
+> job, significantly reducing startup latency.
 
 This module adds paths of a target Conda environment to `PATH`/`Path` while
 activating the environment, and recover the original `PATH`/`Path` while
@@ -30,13 +34,13 @@ deactivating an environment. Several environment variables are exported:
 - `CONDA_BASE_PATH`: The original `PATH`/`Path` before any activation/deactivation.
 - `CONDA_ROOT`: Root directory of Conda installation.
 - `CONDA_ENVS`: Available Conda environments for activation.
-- `CONDA_CURR`: Current activated Conda environments.
+- `CONDA_CURR`: Current activated Conda environment.
 
 
 ## FAQ
 **Q**: How better is the performance?\
-**A**: Activating a Conda environment costs ~20ms while conda.nu costs ~1500ms on
-a PC with Windows 10 Enterprise OS and Intel i7-8700 3.20GHz CPU.
+**A**: Activating a Conda environment costs ~20ms while conda.nu costs ~1500ms
+on a PC with Windows 10 Enterprise OS and Intel i7-8700 3.20GHz CPU.
 
 **Q**: How to show the current Conda environment in the prompt?\
 **A**: This module does not automatically change the prompt when a Conda
@@ -46,15 +50,14 @@ prompt.
 
 
 **Q**: Does it support Mamba/Micromamba?\
-**A**: As [Mamba's documentation](https://mamba.readthedocs.io/en/latest/) said,
-`mamba` is drop-in replacement for `conda`, and `micromamba` seems to be
+**A**: As [Mamba's documentation](https://mamba.readthedocs.io/en/latest/)
+said, `mamba` is drop-in replacement for `conda`, and `micromamba` seems to be
 another thing. This module only uses results of `conda/mamba info --envs --json`.
-Therefore, I would say Mamba is (partially?) supported but I'm not sure about
-Micromamba.
+Therefore, I would say Mamba is supported, but I'm not sure about Micromamba.
 
 
 **Q**: How does it choose between Conda and Mamba?\
-**A**: This module prefers calling `mamba` than `conda`, but it should be very
+**A**: This module prefers calling `mamba` over `conda`, but it should be very
 easy to change the preference by modifying the source code.
 
 

modules/virtual_environments/nu_conda/nu_conda.nu

@@ -1,30 +1,15 @@
+use std-rfc/kv *
+
 export-env {
-  if not ("CONDA_CURR" in $env) {
-    $env.CONDA_BASE_PATH = (if $nu.os-info.name == 'windows' {$env.Path} else {$env.PATH})
-
-    let info = (
-        if not (which mamba | is-empty) {
-          (mamba info --envs --json | from json)
-        } else if not (which conda | is-empty) {
-          (conda info --envs --json | from json)
-        } else {
-          ('{"root_prefix": "", "envs": ""}' | from json)
-        })
-
-    $env.CONDA_ROOT = $info.root_prefix
-
-    $env.CONDA_ENVS = ($info.envs | reduce -f {} {|it, acc|
-        if $it == $info.root_prefix {
-          $acc | upsert "base" $it
-        } else {
-          $acc | upsert ($it | path basename) $it
-        }})
-
-    $env.CONDA_CURR = null
-  }
+  job spawn {find}
 }
 
 export def --env activate [name: string] {
+  if ($env.CONDA_ENVS? | is-empty) {
+    find
+    kv get "conda envars" | load-env
+  }
+
   if ($env.CONDA_ROOT | is-empty) {
     print "Neither Conda nor Mamba is available."
     return
@@ -37,7 +22,7 @@ export def --env activate [name: string] {
   }
 
   let new_path = (
-    if $nu.os-info.name == 'windows' {
+    if ($nu.os-info.name == "windows") {
       update-path-windows ($env.CONDA_ENVS | get $name)
     } else {
       update-path-linux ($env.CONDA_ENVS | get $name)
@@ -47,23 +32,71 @@ export def --env activate [name: string] {
 }
 
 export def --env deactivate [] {
+  if ($env.CONDA_ENVS? | is-empty) {
+    find
+    kv get "conda envars" | load-env
+  }
+
   if ($env.CONDA_ROOT | is-empty) {
     print "Neither Conda nor Mamba is available."
     return
   }
 
-  $env.CONDA_CURR = null
+  $env.CONDA_CURR = ""
 
   load-env {Path: $env.CONDA_BASE_PATH, PATH: $env.CONDA_BASE_PATH}
 }
 
-export def --env list [] {
-  $env.CONDA_ENVS |
-    flatten |
-    transpose |
-    rename name path |
-    insert active { |it| $it.name == $env.CONDA_CURR } |
-    move path --after active
+export def find [] {
+  let $base_path = (if ($nu.os-info.name == "windows") {$env.Path} else {$env.PATH})
+
+  let info = (
+      if not (which mamba | is-empty) {
+        (mamba info --envs --json | from json)
+      } else if not (which conda | is-empty) {
+        (conda info --envs --json | from json)
+      } else {
+        ('{"root": "", "envs": []}' | from json)
+      })
+
+  let info = (
+      if not ("root" in $info) {
+        $info | insert root $info.envs.0
+      } else {
+        $info
+      })
+
+  let $root = $info.root
+
+  let $envs = ($info.envs | reduce -f {} {|it, acc|
+      if $it == $info.root {
+        $acc | upsert "base" $it
+      } else {
+        $acc | upsert ($it | path basename) $it
+      }})
+
+  let $vars = {
+    CONDA_BASE_PATH: $base_path,
+    CONDA_CURR: "",
+    CONDA_ROOT: $root,
+    CONDA_ENVS: $envs
+  }
+
+  kv set "conda envars" $vars
+}
+
+export def list [] {
+  if ($env.CONDA_ENVS? | is-empty) {
+    find
+    kv get "conda envars" | load-env
+  }
+
+  $env.CONDA_ENVS
+    | flatten
+    | transpose
+    | rename name path
+    | insert active {|it| $it.name == $env.CONDA_CURR}
+    | move path --after active
 }
 
 def update-path-linux [env_path: path] {