# replaceFirstMapped method

String replaceFirstMapped (Pattern from, String replace(Match match), [ int startIndex = 0 ])

Replace the first occurrence of `from` in this string.

Returns a new string, which is this string except that the first match of `from`, starting from `startIndex`, is replaced by the result of calling `replace` with the match object.

The optional `startIndex` is by default set to 0. If provided, it must be an integer in the range `[0 .. len]`, where `len` is this string's length.

## Implementation

    String replaceFirstMapped(Pattern from, String replace(Match match),
        [int startIndex = 0]);