Agda.Utils.Char

Agda strings uses Data.Text [1], which can only represent unicode scalar values [2], excluding the surrogate code points 3. To allow primStringFromList to be injective we make sure character values also exclude surrogate code points, mapping them to the replacement character U+FFFD.

See #4999 for more information.

1

https://hackage.haskell.org/package/text-1.2.4.0/docs/Data-Text.html#g:2

2

https://www.unicode.org/glossary/#unicode_scalar_value

3

https://www.unicode.org/glossary/#surrogate_code_point

Documentation

replacementChar :: Char

The unicode replacement character � .

isSurrogateCodePoint :: Char -> Bool

Is a character a surrogate code point.

replaceSurrogateCodePoint :: Char -> Char

Map surrogate code points to the unicode replacement character.

integerToChar :: Integer -> Char

Total function to convert an integer to a character. Maps surrogate code points to the replacement character U+FFFD.