add basic support for repl interaction in tmux

Define tmux-repl-vertical/horizontal/window commands that optionally
takes the name of an interpreter to start it on a new pane/window. Users
then can select some text in the editor and use [tmux-]send-text command
to send it to the interpreter. Ideally the latter command should be
bound to a key for easier interaction.

rc/tmux.kak

@@ -7,6 +7,8 @@ hook global KakBegin .* %{
         if [ -n "$TMUX" ]; then
             echo "alias global focus tmux-focus"
             echo "alias global new tmux-new-horizontal"
+            echo "alias global repl tmux-repl-horizontal"
+            echo "alias global send-text tmux-send-text"
         fi
     }
 }
@@ -37,6 +39,46 @@ def tmux-new-window -params .. -command-completion -docstring "Create a new wind
     tmux-new-impl 'new-window' %arg{@}
 }
 
+def -hidden -params 1..2 tmux-repl-impl %{
+    %sh{
+        if [ -z "$TMUX" ]; then
+            echo "echo -color Error This command is only available in a tmux session"
+            exit
+        fi
+        tmux_args="$1"
+        shift
+        tmux_cmd="$@"
+        tmux $tmux_args $tmux_cmd
+        tmux set-buffer -b kak_repl_window $(tmux display-message -p '#I')
+        tmux set-buffer -b kak_repl_pane $(tmux display-message -p '#P')
+    }
+}
+
+def tmux-repl-vertical -params 0..1 -command-completion -docstring "Create a new vertical pane in tmux for repl interaction" %{
+    tmux-repl-impl 'split-window -v' %arg{@}
+}
+
+def tmux-repl-horizontal -params 0..1 -command-completion -docstring "Create a new horizontal pane in tmux for repl interaction" %{
+    tmux-repl-impl 'split-window -h' %arg{@}
+}
+
+def tmux-repl-window -params 0..1 -command-completion -docstring "Create a new window in tmux for repl interaction" %{
+    tmux-repl-impl 'new-window' %arg{@}
+}
+
+def tmux-send-text -docstring "Send selected text to the repl pane in tmux" %{
+    %sh{
+        tmux set-buffer -b kak_selection "${kak_selection}"
+        kak_orig_window=$(tmux display-message -p '#I')
+        kak_orig_pane=$(tmux display-message -p '#P')
+        tmux select-window -t:$(tmux show-buffer -b kak_repl_window)
+        tmux select-pane -t:.$(tmux show-buffer -b kak_repl_pane)
+        tmux paste-buffer -b kak_selection
+        tmux select-window -t:${kak_orig_window}
+        tmux select-pane -t:.${kak_orig_pane}
+    }
+}
+
 def -docstring "focus given client" \
     -params 0..1 -client-completion \
     tmux-focus %{ %sh{