Characters should be an Extended Grapheme Cluster, corresponding to a single display character.

Chars are “Extended Grapheme Clusters”. (A codepoint is some bytes that implement unicode characters, a grapheme is some codepoints forming a unicode entity, such as an emoji; an EGC is some graphemes, used to handle things like emojis which combine to form a single emoji).

Dark v1 problems

Can't create characters

Problem: Characters were implemented, but you couldn't create one.

Solution: implement characters creation

No character stdlib

Problem: Characters were implemented but there were no functions on characters (they were on strings instead)

Solution: Add functions the use characters

v2 spec

v2 Language definition

type egcChar = // type suitable to hold an EGC

type Expr =
  | EChar { val = egcChar }
  | ...

type Pattern =
  | PChar { val : egcChar }
  | ...

type Dval =
  | DChar { val = egcChar }
  | ...

type DType =
  | TChar
  | ...

v2 Standard library: dark/stdlib/Char

// New
Character::toString(Char: c) -> String
String::map(String: s, (Char -> Char)) -> String
String::toList(String: s) -> List Char
String::fromList(l : List Char) -> String

v2 Editor changes

  • allow entering characters
    • ' creates a partial showing ''
    • entering a character turns the partial into an ECharacter (eg 'a')
    • entering another character turns it into a Partial with both characters (eg 'ab')
    • converting it back into a properly formed character turns it into one
    • typing ' when when your cursor is on the closing quote skips over it
  • escaping should be supported
    • common expected escapes: \n, \r, \t
    • escapes that are needed for the text to work \\, \'
    • allow a specific byte: \xhh (hex escaping)
    • could possibly allow octal escaping too
    • escape sequences should be clear to the user (a different color)
    • escape sequence should have a clear doc explaining how it works and what the user is looking at
    • the expr should be a partial while the \ is not followed by a valid character