Add Windows support for venv

As with the Conda script, a few differences have to be considered
when activating on Windows, namely that the correct env var is Path
and the directory containing the executables is "Scripts", not "bin"

virtual_environments/venv.nu

@@ -1,12 +1,25 @@
-def venv [name] {
-	let venv-path = ($name | path expand)
-	let venv-bin-path = ([$venv-path "bin"] | path join)
+def venv [venv-dir] {
+	let venv-abs-dir = ($venv-dir | path expand)
+	let venv-name = ($venv-abs-dir | path basename)
 	let old-path = ($nu.path | str collect (path-sep))
-	let new-path = ($nu.path | prepend $venv-bin-path | str collect (path-sep))
-	[[name, value];
-	 [PATH $new-path]
+	let new-path = (if (windows?) { (venv-path-windows $venv-abs-dir) } { (venv-path-unix $venv-abs-dir) })
+	let new-env = [[name, value];
 	 [VENV_OLD_PATH $old-path]
-	 [VIRTUAL_ENV $venv-path]]
+	 [VIRTUAL_ENV $venv-name]]
+
+	$new-env | append $new-path
+}
+
+def venv-path-unix [venv-dir] {
+	let venv-path = ([$venv-dir "bin"] | path join)
+	let new-path = ($nu.path | prepend $venv-path | str collect (path-sep))
+	[[name, value]; [PATH $new-path]]
+}
+
+def venv-path-windows [venv-dir] {
+	let venv-path = ([$venv-dir "Scripts"] | path join)
+	let new-path = ($nu.path | prepend $venv-path | str collect (path-sep))
+	[[name, value]; [Path $new-path]]
 }
 
 def windows? [] {
@@ -16,4 +29,3 @@ def windows? [] {
 def path-sep [] {
     if (windows?) { ";" } { ":" }
 }
-

virtual_environments/venv_deactivate.nu

@@ -1,3 +1,4 @@
-let-env PATH = $nu.env.VENV_OLD_PATH
+let path-name = (if ((sys).host.name == "Windows") { "Path" } { "PATH" })
+let-env $path-name = $nu.env.VENV_OLD_PATH
 unlet-env VIRTUAL_ENV
 unlet-env VENV_OLD_PATH