Telehack BASIC (TeleBASIC) — VS Code Syntax Highlighting

Made by GunpointG Updated August 22, 2025

Syntax highlighting for Telehack’s BASIC dialect (aka TeleBASIC).
Covers line-numbered BASIC, REM / ' comments, strings, numbers, TeleBASIC keywords, predefined constants and functions, $/%-suffixed variables, file-descriptor numbers after #, and operators.

Features

• Line numbers at BOL (e.g., 10, 200)
• Comments: REM ... and ' ...
• Strings: double-quoted, with "" escape
• Keywords: IF/THEN, FOR/NEXT, GOTO/GOSUB/RETURN, OPEN $s, AS #n, PRINT, PUT, READ, LET, END, SYSTEM, TH_EXEC, etc.
• Predefined constants (e.g., ARGC%, ARGV$, TIME$, TIMER, TH_*)
• Predefined functions (e.g., ASC, CHR$, INT, LEN, MID$, LEFT$, RIGHT$, RND, TAB$, TH_SPRINTF$, …)
• Variables:
  • String vars: name$
  • Integer vars: count%, count
  • File descriptor numbers (e.g., PRINT #1, ..., INPUT# 2, ...)
• Operators: + - * / = <> <= >= < >
• DEF FN definition highlighting**:**
  • DEF FNname (no-space) → function name tokenized
  • DEF FN name (spaced) → DEF FN as keywords, name as function

The grammar is case-insensitive where appropriate.

Example

10 REM Demo of TeleBASIC syntax
20 ' A comment style
30 A% = 42 : A$ = "hello ""world"""
40 IF A% > 10 THEN PRINT "A is greater than 10"
50 PRINT "User: " + USER$ + "  Time: " + TIME$
60 OPEN "DATA.DAT" AS #1
70 PRINT #1, "Record", A$
80 CLOSE #1
90 DEF FN concat$(X$, Y$) = X$ + Y$
100 PRINT concat$("foo", "bar")
110 PRINT "Arg count=" + STR$(ARGC%)
120 END

File Types

Associated by default with:

• .bas

Scopes & Theming Notes

The grammar uses canonical TextMate scopes so themes can colorize predictably:

• Keywords: keyword.control.telebasic
• Operators: keyword.operator.telebasic
• Strings: string.quoted.double.telebasic (+ constant.character.escape.telebasic)
• Numbers: constant.numeric.telebasic
• Comments:
  • REM ... → comment.line.rem.telebasic
  • ' ... → comment.line.apostrophe.telebasic
• Variables:
  • name$ → variable.other.string.telebasic
  • count% → variable.other.integer.telebasic
  • count → variable.other.telebasic
  • #1 (after #) → variable.other.file-descriptor.telebasic
• Predefined constants: constant.language.telebasic
• Predefined functions: support.function.telebasic

Language Configuration

• Line comments: ', REM
• Auto-closing pairs: "...", (...), [...]

TeleBASIC Dialect Notes

• Single-line IF THEN (classic BASIC style). Use : to chain, or GOTO/GOSUB for multi-line logic.
• Strings are single-line; use concatenation or DATA/READ for longer text.
• DEF FN supports both DEF FNname (no space) and DEF FN name (spaced) patterns in this grammar.

Known Limitations

• No multi-line comment syntax (TeleBASIC doesn’t define one).

Contact

Please reach out to auteur_wand.2u@icloud.com regarding any bugs, issues, or additions needed.