python: interactive console imports sympy by default

src/dot_config/pythonstartup.py

@@ -0,0 +1,7 @@
+try:
+    from sympy import init_session, Rational
+    init_session()
+
+    R = Rational
+except ImportError:
+    pass

src/dot_config/vars.tmpl

@@ -8,6 +8,9 @@ export VARS_SET=1
 # by default chmod o-rwx
 umask 007
 
+# python rc/startup file
+export PYTHONSTARTUP="$HOME/.config/pythonstartup.py"
+
 # Set XDG directories
 export XDG_CONFIG_HOME="$HOME"/.config
 export XDG_CACHE_HOME="$HOME"/.cache