add black as a formatter and format stuff with it

dotfiles/kakoune.nix

@@ -146,6 +146,24 @@ in {
           option = ".*.hs";
         }
 
+        # Python
+        {
+          name = "WinCreate";
+          option = ".*.py";
+          commands = ''
+            evaluate-commands %sh{
+              if which black > /dev/null; then
+                echo 'set-option buffer formatcmd "black - --quiet --fast"'
+              fi
+            }
+          '';
+        }
+        {
+          commands = "format";
+          name = "BufWritePre";
+          option = ".*.py";
+        }
+
         # Indents
         {
           name = "WinCreate";

occasional-scripts/chapters.py

@@ -3,7 +3,7 @@ from __future__ import print_function, unicode_literals
 import argparse
 
 parser = argparse.ArgumentParser()
-parser.add_argument('num_chapters', type=int)
+parser.add_argument("num_chapters", type=int)
 args = parser.parse_args()
 
 task_templates = [
@@ -12,6 +12,6 @@ task_templates = [
     "make flashcards for chapter {}",
 ]
 
-for i in range(1, args.num_chapters+1):
+for i in range(1, args.num_chapters + 1):
     for template in task_templates:
         print(template.format(i))

occasional-scripts/flashcardify.py

@@ -3,12 +3,12 @@ import sys
 import argparse
 
 parser = argparse.ArgumentParser()
-parser.add_argument('--name', default=None)
+parser.add_argument("--name", default=None)
 args = parser.parse_args()
 
-for line in sys.stdin.read().split('\n'):
-    out = line.strip('- ').split('|')
+for line in sys.stdin.read().split("\n"):
+    out = line.strip("- ").split("|")
     if args.name is not None:
         out.append(args.name)
 
-    print('\t'.join(out))
+    print("\t".join(out))

shell.nix

@@ -10,6 +10,9 @@ stdenv.mkDerivation {
     ## meta-information for managing dotfiles
     niv.niv
 
+    ## formatting
+    python3Packages.black
+
     ## sample projects
     # elm
     # elmPackages.elm