{
  "languages": {
    "ada": "Ada",
    "bash": "Bash",
    "cpp": "C++",
    "csharp": "C#",
    "clojure": "Clojure",
    "go": "Go",
    "haskell": "Haskell",
    "java": "Java",
    "javascript": "JavaScript",
    "nim": "Nim",
    "objectivec": "Objective-C",
    "perl": "Perl",
    "php": "PHP",
    "python": "Python",
    "ruby": "Ruby",
    "rust": "Rust",
    "scala": "Scala",
    "swift": "Swift",
    "typescript": "TypeScript",
    "vbnet": "Visual Basic"
  },
  "structures": {
    "classes": "Classes",
    "control_structures": "Control Structures",
    "data_types": "Data Types",
    "exception_handling": "Exception Handling",
    "functions": "Functions, Methods, and Subroutines",
    "io": "Input and Output",
    "lists": "Lists, Arrays, and Hashed Lists",
    "operators": "Logical and Mathematical/Arithmetic Operators",
    "strings": "Strings"
  }
}

{
  "languages": {
    "ada": "Ada",
    "bash": "Bash",
    "c": "C",
    "cpp": "C++",
    "csharp": "C#",
    "clojure": "Clojure",
    "go": "Go",
    "haskell": "Haskell",
    "java": "Java",
    "javascript": "JavaScript",
    "nim": "Nim",
    "objectivec": "Objective-C",
    "perl": "Perl",
    "php": "PHP",
    "python": "Python",
    "ruby": "Ruby",
    "rust": "Rust",
    "scala": "Scala",
    "swift": "Swift",
    "typescript": "TypeScript",
    "vbnet": "Visual Basic"
  },
  "structures": {
    "classes": "Classes",
    "control_structures": "Control Structures",
    "data_types": "Data Types",
    "exception_handling": "Exception Handling",
    "functions": "Functions, Methods, and Subroutines",
    "io": "Input and Output",
    "lists": "Lists, Arrays, and Hashed Lists",
    "operators": "Logical and Mathematical/Arithmetic Operators",
    "strings": "Strings"
  }
}

Update : added C language
Update : added C language