feat: add uv as installer for python

UV is a very fast installer for python packages
that can be 10-100x faster to resolve packages. This adds
an option for Mason to use it instead of pip to resolve
python packages that are installed via Mason.

More info about the replacement: https://github.com/astral-sh/uv
I have no relationship with uv, it is just very fast and
it would be nice to have updates for packages like sqlfluff take
a lot less time than they currently do to resolve during updates.

README.md

@@ -252,6 +252,10 @@ local DEFAULT_SETTINGS = {
         -- Whether to upgrade pip to the latest version in the virtual environment before installing packages.
         upgrade_pip = false,
 
+        ---@since 1.8.0
+        -- Whether to use uv to install packages instead of pip
+        use_uv      = false,
+
         ---@since 1.0.0
         -- These args will be added to `pip install` calls. Note that setting extra args might impact intended behavior
         -- and is not recommended.

doc/mason.txt

@@ -314,6 +314,10 @@ Example:
             -- Whether to upgrade pip to the latest version in the virtual environment before installing packages.
             upgrade_pip = false,
 
+            ---@since 1.8.0
+            -- Whether to use uv to install packages instead of pip
+            use_uv      = false,
+
             ---@since 1.0.0
             -- These args will be added to `pip install` calls. Note that setting extra args might impact intended behavior
             -- and is not recommended.

lua/mason-core/installer/managers/pypi.lua

@@ -9,22 +9,32 @@ local pep440 = require "mason-core.pep440"
 local platform = require "mason-core.platform"
 local providers = require "mason-core.providers"
 local semver = require "mason-core.semver"
+local settings = require "mason.settings"
 local spawn = require "mason-core.spawn"
 
 local M = {}
 
+local use_uv = settings.current.pip.use_uv
 local VENV_DIR = "venv"
 
 ---@async
 ---@param candidates string[]
 local function resolve_python3(candidates)
     local is_executable = _.compose(_.equals(1), vim.fn.executable)
     a.scheduler()
+    if use_uv then
+        candidates = { "uv" }
+    end
     local available_candidates = _.filter(is_executable, candidates)
     for __, candidate in ipairs(available_candidates) do
         ---@type string
         local version_output = spawn[candidate]({ "--version" }):map(_.prop "stdout"):get_or_else ""
-        local ok, version = pcall(semver.new, version_output:match "Python (3%.%d+.%d+)")
+        local ok, version
+        if use_uv then
+            ok, version = pcall(semver.new, version_output:match "uv (%d+.%d+.%d+)")
+        else
+            ok, version = pcall(semver.new, version_output:match "Python (3%.%d+.%d+)")
+        end
         if ok then
             return { executable = candidate, version = version }
         end
@@ -61,10 +71,10 @@ local function get_versioned_candidates(supported_python_versions)
         { semver.new "3.12.0", "python3.12" },
         { semver.new "3.11.0", "python3.11" },
         { semver.new "3.10.0", "python3.10" },
-        { semver.new "3.9.0", "python3.9" },
-        { semver.new "3.8.0", "python3.8" },
-        { semver.new "3.7.0", "python3.7" },
-        { semver.new "3.6.0", "python3.6" },
+        { semver.new "3.9.0",  "python3.9" },
+        { semver.new "3.8.0",  "python3.8" },
+        { semver.new "3.7.0",  "python3.7" },
+        { semver.new "3.6.0",  "python3.6" },
     })
 end
 
@@ -109,15 +119,17 @@ local function create_venv(pkg)
     then
         if ctx.opts.force then
             ctx.stdio_sink.stderr(
-                ("Warning: The resolved python3 version %s is not compatible with the required Python versions: %s.\n"):format(
+                ("Warning: The resolved python3 version %s is not compatible with the required Python versions: %s.\n")
+                :format(
                     target.version,
                     supported_python_versions
                 )
             )
         else
             ctx.stdio_sink.stderr "Run with :MasonInstall --force to bypass this version validation.\n"
             return Result.failure(
-                ("Failed to find a python3 installation in PATH that meets the required versions (%s). Found version: %s."):format(
+                ("Failed to find a python3 installation in PATH that meets the required versions (%s). Found version: %s.")
+                :format(
                     supported_python_versions,
                     target.version
                 )
@@ -127,7 +139,14 @@ local function create_venv(pkg)
 
     log.fmt_debug("Found python3 installation version=%s, executable=%s", target.version, target.executable)
     ctx.stdio_sink.stdout "Creating virtual environment…\n"
-    return ctx.spawn[target.executable] { "-m", "venv", "--system-site-packages", VENV_DIR }
+
+    if use_uv then
+        log.fmt_debug("Found uv installation version=%s, executable=%s", target.version, target.executable)
+        return ctx.spawn[target.executable] { "venv", VENV_DIR }
+    else
+        log.fmt_debug("Found python3 installation version=%s, executable=%s", target.version, target.executable)
+        return ctx.spawn[target.executable] { "-m", "venv", "--system-site-packages", VENV_DIR }
+    end
 end
 
 ---@param ctx InstallContext
@@ -162,16 +181,29 @@ end
 ---@param pkgs string[]
 ---@param extra_args? string[]
 local function pip_install(pkgs, extra_args)
-    return venv_python {
-        "-m",
-        "pip",
-        "--disable-pip-version-check",
-        "install",
-        "--ignore-installed",
-        "-U",
-        extra_args or vim.NIL,
-        pkgs,
-    }
+    if use_uv then
+        local ctx = installer.context()
+        local task = ctx.spawn["uv"] {
+            "pip",
+            "install",
+            "-U",
+            extra_args or vim.NIL,
+            pkgs,
+        }
+        -- vim.api.nvim_set_current_dir(curdir)
+        return task
+    else
+        return venv_python {
+            "-m",
+            "pip",
+            "--disable-pip-version-check",
+            "install",
+            "--ignore-installed",
+            "-U",
+            extra_args or vim.NIL,
+            pkgs,
+        }
+    end
 end
 
 ---@async
@@ -185,7 +217,7 @@ function M.init(opts)
         ctx:promote_cwd()
         try(create_venv(opts.package))
 
-        if opts.upgrade_pip then
+        if opts.upgrade_pip and not use_uv then
             ctx.stdio_sink.stdout "Upgrading pip inside the virtual environment…\n"
             try(pip_install({ "pip" }, opts.install_extra_args))
         end

lua/mason-core/installer/registry/providers/pypi.lua

@@ -27,6 +27,7 @@ function M.parse(source, purl)
             pip = {
                 upgrade = settings.current.pip.upgrade_pip,
                 extra_args = settings.current.pip.install_args,
+                use_uv = settings.current.pip.use_uv,
             },
         }
 
@@ -48,11 +49,13 @@ function M.install(ctx, source)
             },
             upgrade_pip = source.pip.upgrade,
             install_extra_args = source.pip.extra_args,
+            use_uv = source.pip.use_uv,
         })
         try(pypi.install(source.package, source.version, {
             extra = source.extra,
             extra_packages = source.extra_packages,
             install_extra_args = source.pip.extra_args,
+            use_uv = source.pip.use_uv,
         }))
     end)
 end

lua/mason/settings.lua

@@ -60,6 +60,10 @@ local DEFAULT_SETTINGS = {
         -- Whether to upgrade pip to the latest version in the virtual environment before installing packages.
         upgrade_pip = false,
 
+        ---@since 1.8.0
+        -- Whether to use uv to install packages instead of pip
+        use_uv = false,
+
         ---@since 1.0.0
         -- These args will be added to `pip install` calls. Note that setting extra args might impact intended behavior
         -- and is not recommended.

tests/mason-core/installer/registry/providers/pypi_spec.lua

@@ -31,6 +31,7 @@ describe("pypi provider :: parsing", function()
                 pip = {
                     upgrade = true,
                     extra_args = { "--proxy", "http://localghost" },
+                    use_uv = false,
                 },
             },
             pypi.parse({ extra_packages = { "extra" } }, purl())