Programmer's Shift Keys: Remapping parens, brackets and braces for to because nerd.

private.xml

<?xml version="1.0"?>
<root>
    <item>
      <name>Programmer's Shift Keys</name>
      <!--
          Author: Carwin Young (@carwin)
          Last Updated: 2014.07.18
          v.1.1
          
          Programmer's Shift Keys
          A private.xml for Karabiner (formerly KeyRemap4MacBook)
          
          This private.xml file can be either chopped up for copy-pasting, or
          used alone and modified if you don't already have your own file.
          If you want to use it, add this file to
          ~/Library/Application\ Support/KeyRemap4MacBook/
          
          Options:
              - Parens:     Maps individual strokes of the Shift keys to their 
                            respective parenthesis keys.
              - Brackets:   Pairs Command and Shift keys to produce brackets.
              - Braces:     Pairs Option and Shift keys to produce braces.
                  
                  
      </-->
      <item>
          <name>Parentheses ()</name>
          <!-- Credit for this Parens section goes to Steve Losh: http://stevelosh.com/blog/2012/10/a-modern-space-cadet/ -->
          <appendix>Shifts, when pressed alone, type parentheses.  When used with other keys they're normal shifts.</appendix>
          <identifier>private.shifts_to_parens</identifier>
          <autogen>--KeyOverlaidModifier-- KeyCode::SHIFT_R, ModifierFlag::SHIFT_R | ModifierFlag::NONE, KeyCode::SHIFT_R, KeyCode::KEY_0, ModifierFlag::SHIFT_L</autogen>
          <autogen>--KeyOverlaidModifier-- KeyCode::SHIFT_L, ModifierFlag::SHIFT_L | ModifierFlag::NONE, KeyCode::SHIFT_L, KeyCode::KEY_9, ModifierFlag::SHIFT_R</autogen>
          <!--
              Remap the "rolls" of () and )( because it's too easy to hit one
              before finishing the other, and there's no other reason to be
              pressing both shift keys at once anyway
          -->
          <autogen>--KeyToKey-- KeyCode::SHIFT_L, ModifierFlag::SHIFT_R, KeyCode::KEY_0, ModifierFlag::SHIFT_L, KeyCode::KEY_9, ModifierFlag::SHIFT_L</autogen>
          <autogen>--KeyToKey-- KeyCode::SHIFT_R, ModifierFlag::SHIFT_L, KeyCode::KEY_9, ModifierFlag::SHIFT_L, KeyCode::KEY_0, ModifierFlag::SHIFT_L</autogen>
          <!--
              Remap Rshift+Space to ') ', because when typing an end paren and
              then a space I tend to hit space before I let go of rshift.
          -->
          <autogen>--KeyToKey-- KeyCode::SPACE, ModifierFlag::SHIFT_R, KeyCode::KEY_0, ModifierFlag::SHIFT_L, KeyCode::SPACE</autogen>
          <!--
              Steve also suggests setting the Key Overlaid Modifier Timeout
              setting to a much lower value. I use 200ms.
          -->
      </item>
      <item>
        <name>Brackets []</name>
        <appendix>Remap Command+Shift to brackets.</appendix>
        <identifier>private.shifts_to_brackets</identifier>
        <autogen>--KeyOverlaidModifier-- KeyCode::SHIFT_R, ModifierFlag::SHIFT_R | ModifierFlag::COMMAND_R, KeyCode::BRACKET_RIGHT, ModifierFlag::NONE</autogen>
        <autogen>--KeyOverlaidModifier-- KeyCode::SHIFT_L, ModifierFlag::SHIFT_L | ModifierFlag::COMMAND_L, KeyCode::BRACKET_LEFT, ModifierFlag::NONE</autogen>
        <!--
            Another way to do this that I like a lot is to actually map the
            brackets to a SIMULTANEOUS keypress of SHIFT + COMMAND.
        
        <autogen>
            __SimultaneousKeyPresses__
            KeyCode::COMMAND_L, KeyCode::SHIFT_L,
            KeyCode::BRACKET_LEFT,
            Option::SIMULTANEOUSKEYPRESSES_STRICT_KEY_ORDER
        </autogen>

        <autogen>
            __SimultaneousKeyPresses__
            KeyCode::COMMAND_R, KeyCode::SHIFT_R,
            KeyCode::BRACKET_RIGHT,
            Option::SIMULTANEOUSKEYPRESSES_STRICT_KEY_ORDER
        </autogen>
        -->
      </item>

      <item>
        <name>Braces {}</name>
        <appendix>Remap Option+Shift to braces.</appendix>
        <identifier>private.shifts_to_braces</identifier>
        <autogen>--KeyOverlaidModifier-- KeyCode::SHIFT_R, ModifierFlag::SHIFT_R | ModifierFlag::OPTION_R, KeyCode::BRACKET_RIGHT, ModifierFlag::SHIFT_R</autogen>
        <autogen>--KeyOverlaidModifier-- KeyCode::SHIFT_L, ModifierFlag::SHIFT_L | ModifierFlag::OPTION_L, KeyCode::BRACKET_LEFT, ModifierFlag::SHIFT_L</autogen>
      </item>

  </item>
</root>

Why use the combo of Command+Shift? Why not use Command alone for brackets and Option alone for braces?

^ in case anyone's curious: this doesn't work out very well (for me at least). Unlike shift, command and option will key-repeat, so they're likely to spit out a bunch of brackets/braces. It also seems to mess things up like command-arrowkeys (and variations) for text navigation, command-tab, etc.