Karabiner complex rule for balanced delimiter mapping

karabiner.json

// Karabiner complex ruleset for convenient balanced delimiter mapping (macOS).
// To install, follow these steps:
// 1. Install Karabiner and give it permission to capture from your keyboard in System Preferences.
// 2. Go to "complex modifications" and click on "add your own rule".
// 3. Paste the below JSON configuration into the text box that opens, and click "save".
// Here are all of the mappings that it defines:
// - Map Ctrl+9 to (), placing cursor between parens
// - Map Ctrl+[ to [], placing cursor between brackets
// - Map Ctrl+] to {}, placing cursor between parens
// - Map Ctrl+4 to $$, placing cursor between dollar signs (for LaTeX)
// - Map Ctrl+, to <>, placing cursor between brackets
{
    "description": "Ruleset for convenient balanced delimiters",
    "manipulators": [
        // Map Ctrl+9 to (), placing cursor between parens
        {
            "from": {
                "key_code": "9",
                "modifiers": {
                    "mandatory": [
                        "left_control"
                    ],
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "9",
                    "modifiers": [
                        "left_shift"
                    ]
                },
                {
                    "key_code": "0",
                    "modifiers": [
                        "left_shift"
                    ]
                },
                {
                    "key_code": "left_arrow"
                }
            ],
            "type": "basic"
        },
        // Map Ctrl+[ to [], placing cursor between brackets
        {
            "from": {
                "key_code": "open_bracket",
                "modifiers": {
                    "mandatory": [
                        "left_control"
                    ],
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "open_bracket"
                },
                {
                    "key_code": "close_bracket"
                },
                {
                    "key_code": "left_arrow"
                }
            ],
            "type": "basic"
        },
        // Map Ctrl+] to {}, placing cursor between parens
        {
            "from": {
                "key_code": "close_bracket",
                "modifiers": {
                    "mandatory": [
                        "left_control"
                    ],
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "open_bracket",
                    "modifiers": [
                        "left_shift"
                    ]
                },
                {
                    "key_code": "close_bracket",
                    "modifiers": [
                        "left_shift"
                    ]
                },
                {
                    "key_code": "left_arrow"
                }
            ],
            "type": "basic"
        },
        // Map Ctrl+4 to $$, placing cursor between dollar signs (for LaTeX)
        {
            "from": {
                "key_code": "4",
                "modifiers": {
                    "mandatory": [
                        "left_control"
                    ],
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "4",
                    "modifiers": [
                        "left_shift"
                    ]
                },
                {
                    "key_code": "4",
                    "modifiers": [
                        "left_shift"
                    ]
                },
                {
                    "key_code": "left_arrow"
                }
            ],
            "type": "basic"
        },
        // Map Ctrl+, to <>, placing cursor between brackets
        {
            "from": {
                "key_code": "comma",
                "modifiers": {
                    "mandatory": [
                        "left_control"
                    ],
                    "optional": [
                        "any"
                    ]
                }
            },
            "to": [
                {
                    "key_code": "comma",
                    "modifiers": [
                        "left_shift"
                    ]
                },
                {
                    "key_code": "period",
                    "modifiers": [
                        "left_shift"
                    ]
                },
                {
                    "key_code": "left_arrow"
                }
            ],
            "type": "basic"
        }
    ]
}