#lang at-exp scheme
(require scheme/system scheme/gui/base)

(define str string-append)

(define TEMPLATE
  @str{\documentclass{article}
       \usepackage[mathletters]{ucs}
       \usepackage[utf8x]{inputenc}
       \usepackage{amsmath}
       \pagestyle{empty}
       \begin{document}
       \Huge\[
       ~a
       \]
       \end{document}})

(define COMMANDS
  @str{pdflatex x.tex
       convert -density 96x96 x.pdf -trim +repage x.png})

(define (latex . strs)
  (define latex (make-temporary-file "latex~a" 'directory))
  (define (run)
    (parameterize ([current-directory latex]
                   [current-input-port (open-input-bytes #"")]
                   [current-output-port (open-output-string)])
      (call-with-output-file* "x.tex" #:exists 'truncate
        (lambda (o) (fprintf o TEMPLATE (string-append* strs))))
      (unless (system (regexp-replace #rx"\n+" COMMANDS " \\&\\& "))
        (display (get-output-string (current-output-port))
                 (current-error-port))
        (error 'latex
               "commands did not run successfully, see above output"))
      (make-object image-snip% "x.png")))
  (define (cleanup) (delete-directory/files latex))
  (dynamic-wind void run cleanup))

;; Examples
@latex{\sum_{i=0}^{\infty}\lambda_i}
(let ([self @str{\lambda x . x x}])
  @latex{(@self) (@self)})