#lang scheme/base

(require scheme/list)
(require scheme/path)

(provide read-module)

(define (read-module [port (current-input-port)])
  `(lambda *argv*
     ,@(let iter ([forms (read-forms port)]
                  [bindings '()])
         (match forms
           ['()
            (if (null? bindings)
                '()
                `((letrec ,(reverse bindings))))]
           [`((define ,var ,expr) . ,rst)
            (iter rst (cons (list var expr) bindings))]
           [`((define (,var . ,arglist) . ,body) . ,rst)
            (iter rst (cons (list var `(lambda ,arglist ,@body)) bindings))]
           [`((define . ,_) . ,_)
            (error "Unrecognized define-form:" (first forms))]
           [`((begin . ,body) . ,rst)
            (iter (append body rst) bindings)]
           [`((load ,(? string? pathname)) . ,rst)
            (let ([complete-path (path->complete-path pathname)]
                  [directory (path-only complete-path)])
              (iter (append (with-input-from-file complete-path
                              (lambda ()
                                (parameterize ([current-directory directory])
                                  (read-forms))))
                            rst)
                    bindings))]
           [`((load . ,_) . ,rst)
            (error "Unrecognized load-form:" (first forms))]
           [(,form . ,rst)
            (if (null? bindings)
                (cons form (iter rst '()))
                `((letrec ,(reverse bindings)
                    ,@(cons form (iter rst '())))))]))))

(define (read-forms [port (current-input-port)])
  (reverse (let iter ([form (read port)]
                      [forms '()])
             (if (eof-object? form)
                 forms
                 (iter (read port) (cons form forms))))))

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