index.cs

// C#
List<string> keywords = ...;
var result = keywords
    .GroupBy(k => k[0].ToUpper())
    .ToDictionary(
        g => g.Key,
        g => g.OrderBy(k => k).ToList());

index.fs

// F#
let keywords = ...
let result = 
    keywords
    |> Seq.groupBy (fun k -> k.[0].ToUpper())
    |> Seq.map (fun (k, v) -> (k, v |> Seq.sort |> List.ofSeq))
    |> Map.ofSeq

index.java

// Java
List<String> keywords = ...;
Map<Character, List<String>> result = new HashMap<Character, List<String>>();

for (String k: keywords) {
    char firstChar = k.charAt(0);

    if (!result.containsKey(firstChar)) {
        result.put(firstChar, new ArrayList<String>());
    }

    result.get(firstChar).add(k);
}

for (List<String> list: result.values()) {
    Collections.sort(list);
}

index.js

// JavaScript（基于类库扩展）
var keywords = ...;
var result = keywords
    .groupBy(function (k) { return k[0].toUpperCase(); })
    .each(function (key, value) { value.sort(); });

index.rb

# Ruby
keywords = ...
result = keywords \
    .group_by { |k| k[0,1].upcase } \
    .each { |key, value| value.sort! }