check if installed first, add xclip for vim clipboard

scripts/04_setup_languages.sh

@@ -1,13 +1,26 @@
 #!/bin/bash
 
+installed() {
+  if command -v "$1" > /dev/null 2>&1 ; then
+    return 0
+  fi
+  return 1
+}
+
 # python
-sudo pacman -S --noconfirm python python-pip
+if ! installed "python" ; then
+  sudo pacman -S --noconfirm python python-pip
+fi
 
 # node
-sudo pacman -S --noconfirm nvm
-source /usr/share/nvm/init-nvm.sh
-nvm install node
+if ! installed "node" ; then
+  yay -S --noconfirm nvm
+  source /usr/share/nvm/init-nvm.sh
+  nvm install node
+fi
 
-#sudo pacman -S --noconfirm rustup
-rustup default stable
+if ! installed "cargo" ; then
+  sudo pacman -S --noconfirm rustup
+  rustup default stable
+fi