Command strategies; restore vim sessions

Closes #4

strategies/vim_session.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+# "vim session strategy"
+#
+# Restores a vim session from 'Session.vim' file, if it exists.
+# If 'Session.vim' does not exist, it falls back to invoking the original
+# command.
+
+ORIGINAL_COMMAND="$1"
+DIRECTORY="$2"
+
+vim_session_file_exists() {
+	[ -e "${DIRECTORY}/Session.vim" ]
+}
+
+main() {
+	if vim_session_file_exists; then
+		echo "vim -S"
+	else
+		echo "$ORIGINAL_COMMAND"
+	fi
+}
+main