src/sigil/telegram/format.sgl

1;;; (sigil telegram format) - MarkdownV2 Formatting Helpers

2;;;

3;;; Provides escaping and formatting functions for Telegram's MarkdownV2

4;;; parse mode. Dynamic text must be escaped with `tg-escape-markdown`

5;;; before wrapping with formatting helpers.

7(define-library (sigil telegram format)

8 (import (sigil core)

9 (sigil string))

11 (export

12 tg-escape-markdown

13 tg-bold

14 tg-italic

15 tg-underline

16 tg-strike

17 tg-code

18 tg-code-block

19 tg-link

20 tg-spoiler)

22 (begin

24 ;; Characters that must be escaped in MarkdownV2 outside of formatting

25 (define %markdown-special-chars

26 '("_" "*" "[" "]" "(" ")" "~" "`" ">" "#"

27 "+" "-" "=" "|" "{" "}" "." "!"))

29 ;;; Escape a string for Telegram MarkdownV2 format.

30 ;;;

31 ;;; Prepends a backslash before each special character that MarkdownV2

32 ;;; requires to be escaped. Call this on dynamic text before wrapping

33 ;;; it with formatting helpers like `tg-bold` or `tg-italic`.

34 ;;;

35 ;;; ```scheme

36 ;;; (tg-escape-markdown "Hello! How are you?")

37 ;;; ; => "Hello\\! How are you\\?"

38 ;;;

39 ;;; (tg-escape-markdown "Price: $5.00 (USD)")

40 ;;; ; => "Price: $5\\.00 \$USD\$"

41 ;;; ```

42 (define (tg-escape-markdown text)

43 (: string? -> string?)

44 (fold (lambda (result char)

45 (string-replace result char (string-append "\\" char)))

46 text

47 %markdown-special-chars))

49 ;;; Format text as bold in MarkdownV2.

50 ;;;

51 ;;; ```scheme

52 ;;; (tg-bold "important") ; => "*important*"

53 ;;; ```

54 (define (tg-bold text)

55 (: string? -> string?)

56 (string-append "*" text "*"))

58 ;;; Format text as italic in MarkdownV2.

59 ;;;

60 ;;; ```scheme

61 ;;; (tg-italic "emphasis") ; => "_emphasis_"

62 ;;; ```

63 (define (tg-italic text)

64 (: string? -> string?)

65 (string-append "_" text "_"))

67 ;;; Format text as underlined in MarkdownV2.

68 ;;;

69 ;;; ```scheme

70 ;;; (tg-underline "noted") ; => "__noted__"

71 ;;; ```

72 (define (tg-underline text)

73 (: string? -> string?)

74 (string-append "__" text "__"))

76 ;;; Format text as strikethrough in MarkdownV2.

77 ;;;

78 ;;; ```scheme

79 ;;; (tg-strike "removed") ; => "~removed~"

80 ;;; ```

81 (define (tg-strike text)

82 (: string? -> string?)

83 (string-append "~" text "~"))

85 ;;; Format text as inline code in MarkdownV2.

86 ;;;

87 ;;; ```scheme

88 ;;; (tg-code "variable") ; => "`variable`"

89 ;;; ```

90 (define (tg-code text)

91 (: string? -> string?)

92 (string-append "`" text "`"))

94 ;;; Format text as a code block in MarkdownV2.

95 ;;;

96 ;;; Optionally specify a language for syntax highlighting.

97 ;;;

98 ;;; ```scheme

99 ;;; (tg-code-block "(+ 1 2)")

100 ;;; ; => "```\n(+ 1 2)```"

101 ;;;

102 ;;; (tg-code-block "(+ 1 2)" language: "scheme")

103 ;;; ; => "```scheme\n(+ 1 2)```"

104 ;;; ```

105 (define (tg-code-block text (keys: (language #f)))

106 (: string? (language: (maybe string?)) -> string?)

107 (if language

108 (string-append "```" language "\n" text "```")

109 (string-append "```\n" text "```")))

110

111 ;;; Format a MarkdownV2 inline link.

112 ;;;

113 ;;; ```scheme

114 ;;; (tg-link "Click here" "https://example.com")

115 ;;; ; => "[Click here](https://example.com)"

116 ;;; ```

117 (define (tg-link text url)

118 (: string? string? -> string?)

119 (string-append "[" text "](" url ")"))

120

121 ;;; Format text as a spoiler in MarkdownV2.

122 ;;;

123 ;;; ```scheme

124 ;;; (tg-spoiler "hidden text") ; => "||hidden text||"

125 ;;; ```

126 (define (tg-spoiler text)

127 (: string? -> string?)

128 (string-append "||" text "||"))

129

130 ))