application/octet-stream
•
1.45 KB
•
35 lines
[defun quasiquote-real [l depth]
[if [nil? l]
#nil
[if [pair? l]
[if [eq? [caar l] 'unquote-splicing]
[list 'append [cadr [car l]] [quasiquote-real [cdr l] depth]]
[if [eq? [car l] 'unquote]
[if [zero? depth]
[cadr l]
[list 'unquote
[quasiquote-real [cadr l] [-- depth]]]]
[if [eq? [car l] 'quasiquote]
[quasiquote-real [quasiquote-real [cadr l] [++ depth]] depth]
[if [zero? depth]
[list 'cons
[quasiquote-real [car l] depth]
[quasiquote-real [cdr l] depth]]
[cons [quasiquote-real [car l] depth]
[quasiquote-real [cdr l] depth]]]]]]
[if [and [zero? depth] [symbol? l]]
[cons 'quote [cons l]]
l]]]
]
[defmacro quasiquote [l]
[quasiquote-real l 0]
]
[defun unquote [expr]
[throw [list :unquote-without-quasiquote "unquote should only occur inside a quasiquote, never evaluated directly"]]
]
[defun unquote-splicing [expr]
[throw [list :unquote-splicing-without-quasiquote "unquote-splicing should only occur inside a quasiquote, never evaluated directly"]]
]
