#lang racket/base (require racket/base) ;; Special purpose zipper for building lambda/let expressions: ;; (state ((lambda (state) #f))) :: >> (define (stx-zip-up stx) (syntax-case stx () ((node ((siblings ...) parent)) #`((siblings ... node) parent)))) (define (stx-zip-down stx) (syntax-case stx () (( (siblings ... node) parent) #`(node ((siblings ...) parent))))) (define (stx-zipper->tree stx) (syntax-case stx () ((node #f) #'node) (_ (stx-zipper->tree (stx-zip-up stx))))) (define (stx-tree->zipper stx) #`(#,stx #f))