Modify fish config and prompt to check for commands before running;

cache programming language versions to improve prompt speed

.config/fish/config.fish

@@ -10,11 +10,8 @@ set -gx PATH $PATH $GOBIN \
     $HOME/.cargo/bin \
     $HOME/.dotnet/tools
 
-set -g fish_escape_delay_ms 10
-
-kitty + complete setup fish | source
-
-source (brew --prefix asdf)/asdf.fish
+command -sq kitty; and kitty + complete setup fish | source
+command -sq asdf; and source (brew --prefix asdf)/asdf.fish
 
 # The next line updates PATH for the Google Cloud SDK.
 # if test -f '/Users/m/Documents/google-cloud-sdk/path.fish.inc'; source '/Users/m/Documents/google-cloud-sdk/path.fish.inc'; end

.config/fish/functions/fish_prompt.fish

@@ -4,11 +4,6 @@ function fish_prompt --description 'Write out the prompt'
     set -l suffix
     set -l user_prefix
     set -l git_branch
-    set -l go_version
-    set -l docker_version
-    set -l node_version
-    set -l ex_version
-    set -l dart_version
     set -l jobs_num
     set -l exit_code
 
@@ -66,7 +61,7 @@ function fish_prompt --description 'Write out the prompt'
     if test -n "$SSH_CLIENT"; set user_prefix $USER @ (prompt_hostname) ' '; end
 
     # Show current git branch, based on git commands only.
-    if git branch --show-current > /dev/null 2> /dev/null
+    if test -e ./.git; and command -sq git
         set -l branch_color green
         set -l git_status (git status)
 
@@ -96,15 +91,23 @@ function fish_prompt --description 'Write out the prompt'
     end
 
     # Set go version, by existence of go mod or dep files
-    if test -e ./go.mod; or test -e ./Gopkg.toml; and which go > /dev/null
-        set -l version_str (string match -r 'go\d+\.\d+\.?\d*' (go version))
-        set go_version ' with ' (set_color 8eadaf) $version_str (set_color normal)
+    if test -e ./go.mod; or test -e ./Gopkg.toml; and command -sq go
+        if test -z "$go_version"
+            set -l version_str (string match -r 'go\d+\.\d+\.?\d*' (go version))
+            set go_version ' with ' (set_color 8eadaf) $version_str (set_color normal)
+        end
+    else
+        set -g go_version
     end
 
     # Set docker version, by existence of Dockerfile
-    if test -e ./Dockerfile; and which docker > /dev/null
-        set -l version_str (string match -r '\d+\.\d+\.?\d*' (docker --version))
-        set docker_version ' on ' (set_color blue) 'docker' $version_str (set_color normal)
+    if test -e ./Dockerfile; and command -sq docker
+        if test -z "$docker_version"
+            set -l version_str (string match -r '\d+\.\d+\.?\d*' (docker --version))
+            set docker_version ' on ' (set_color blue) 'docker' $version_str (set_color normal)
+        end
+    else
+        set -g docker_version
     end
 
     # Set user prefix, based on docker machine name
@@ -113,26 +116,38 @@ function fish_prompt --description 'Write out the prompt'
     end
 
     # Set node (and ts) version, based on existance of package.json (and tsconfig.json)
-    if test -e ./package.json; and which node > /dev/null
-        set -l version_str (string sub -s 2 (node -v))
-        set node_version ' with ' (set_color brgreen) 'node' $version_str (set_color normal)
+    if test -e ./package.json; and command -sq node
+        if test -z "$node_version"
+            set -l version_str (string sub -s 2 (node -v))
+            set node_version ' with ' (set_color brgreen) 'node' $version_str (set_color normal)
 
-        if test -e ./tsconfig.json; and which tsc > /dev/null
-          set -l version_str (string match -r '\d+\.\d+\.?\d*' (tsc -v))
-          set node_version $node_version ' and ' (set_color cyan) 'ts' $version_str (set_color normal)
+            if test -e ./tsconfig.json; and command -sq tsc
+                set -l version_str (string match -r '\d+\.\d+\.?\d*' (tsc -v))
+                set node_version $node_version ' and ' (set_color cyan) 'ts' $version_str (set_color normal)
+            end
         end
+    else
+        set -g node_version
     end
 
     # Set elixir version, based on existance of mix.exs
-    if test -e ./mix.exs; and which elixir > /dev/null
-        set -l version_str (string sub -s 8 (string match -r 'Elixir \d+\.\d+\.?\d*' (elixir -v)))
-        set ex_version ' with ' (set_color magenta) 'ex' $version_str (set_color normal)
+    if test -e ./mix.exs; and command -sq elixir
+        if test -z "$ex_version"
+            set -l version_str (string sub -s 8 (string match -r 'Elixir \d+\.\d+\.?\d*' (elixir -v)))
+            set ex_version ' with ' (set_color magenta) 'ex' $version_str (set_color normal)
+        end
+    else
+        set -g ex_version
     end
 
     # Set dart version, based on existances of pubspec.yaml
-    if test -e ./pubspec.yaml; and which dart > /dev/null
-        set -l version_str (string match -r '\d+\.\d+\.?\d*' (dart --version 2>| cat))
-        set dart_version ' with ' (set_color brblue) 'dart' $version_str (set_color normal)
+    if test -e ./pubspec.yaml; and command -sq dart
+        if test -z "$dart_version"
+            set -l version_str (string match -r '\d+\.\d+\.?\d*' (dart --version 2>| cat))
+            set dart_version ' with ' (set_color brblue) 'dart' $version_str (set_color normal)
+        end
+    else
+        set -g dart_version
     end
 
     # Combine all prompt variables