(number) @constant.numeric
(character) @constant.character
(boolean) @constant.builtin.boolean

(string) @string

(escape_sequence) @constant.character.escape

(comment) @comment.line
(block_comment) @comment.block
(directive) @keyword.directive

; operators

((symbol) @operator
 (#match? @operator "^(\\+|-|\\*|/|=|>|<|>=|<=)$"))

; keywords

(list
  .
  ((symbol) @keyword.conditional
   (#match? @keyword.conditional "^(if|cond|case|when|unless)$"
  )))
 
(list
  .
  (symbol) @keyword
  (#match? @keyword
   "^(define-syntax|let\\*|lambda|λ|case|=>|quote-splicing|unquote-splicing|set!|let|letrec|letrec-syntax|let-values|let\\*-values|do|else|define|cond|syntax-rules|unquote|begin|quote|let-syntax|and|if|quasiquote|letrec|delay|or|when|unless|identifier-syntax|assert|library|export|import|rename|only|except|prefix)$"
   ))

(list
  .
  (symbol) @function.builtin
  (#match? @function.builtin
   "^(caar|cadr|call-with-input-file|call-with-output-file|cdar|cddr|list|open-input-file|open-output-file|with-input-from-file|with-output-to-file|\\*|\\+|-|/|<|<=|=|>|>=|abs|acos|angle|append|apply|asin|assoc|assq|assv|atan|boolean\\?|caaaar|caaadr|caaar|caadar|caaddr|caadr|cadaar|cadadr|cadar|caddar|cadddr|caddr|call-with-current-continuation|call-with-values|car|cdaaar|cdaadr|cdaar|cdadar|cdaddr|cdadr|cddaar|cddadr|cddar|cdddar|cddddr|cdddr|cdr|ceiling|char->integer|char-alphabetic\\?|char-ci<=\\?|char-ci<\\?|char-ci=\\?|char-ci>=\\?|char-ci>\\?|char-downcase|char-lower-case\\?|char-numeric\\?|char-ready\\?|char-upcase|char-upper-case\\?|char-whitespace\\?|char<=\\?|char<\\?|char=\\?|char>=\\?|char>\\?|char\\?|close-input-port|close-output-port|complex\\?|cons|cos|current-error-port|current-input-port|current-output-port|denominator|display|dynamic-wind|eof-object\\?|eq\\?|equal\\?|eqv\\?|eval|even\\?|exact->inexact|exact\\?|exp|expt|floor|flush-output|for-each|force|gcd|imag-part|inexact->exact|inexact\\?|input-port\\?|integer->char|integer\\?|interaction-environment|lcm|length|list->string|list->vector|list-ref|list-tail|list\\?|load|log|magnitude|make-polar|make-rectangular|make-string|make-vector|map|max|member|memq|memv|min|modulo|negative\\?|newline|not|null-environment|null\\?|number->string|number\\?|numerator|odd\\?|output-port\\?|pair\\?|peek-char|positive\\?|procedure\\?|quotient|rational\\?|rationalize|read|read-char|real-part|real\\?|remainder|reverse|round|scheme-report-environment|set-car!|set-cdr!|sin|sqrt|string|string->list|string->number|string->symbol|string-append|string-ci<=\\?|string-ci<\\?|string-ci=\\?|string-ci>=\\?|string-ci>\\?|string-copy|string-fill!|string-length|string-ref|string-set!|string<=\\?|string<\\?|string=\\?|string>=\\?|string>\\?|string\\?|substring|symbol->string|symbol\\?|tan|transcript-off|transcript-on|truncate|values|vector|vector->list|vector-fill!|vector-length|vector-ref|vector-set!|vector\\?|write|write-char|zero\\?)$"
   ))

; special forms

(list
 "["
 (symbol)+ @variable
 "]")

(list
 .
 (symbol) @_f
 .
 (list
   (symbol) @variable)
 (#eq? @_f "lambda"))

(list
 .
 (symbol) @_f
 .
 (list
   (list
     (symbol) @variable.parameter))
 (#match? @_f
  "^(let|let\\*|let-syntax|let-values|let\\*-values|letrec|letrec\\*|letrec-syntax)$"))

; quote

(list
 .
 (symbol) @_f
 (#eq? @_f "quote")) @string.symbol

; library

(list
 .
 (symbol) @_lib
 .
 (symbol) @namespace

 (#eq? @_lib "library"))

; procedure

(list
  .
  (symbol) @function)

;; variables

((symbol) @variable.builtin
 (#eq? @variable.builtin "..."))

((symbol) @variable.builtin
 (#eq? @variable.builtin "."))

(symbol) @variable

["(" ")" "[" "]" "{" "}"] @punctuation.bracket