29 lines
965 B
Racket
29 lines
965 B
Racket
#lang scheme/base
|
|
|
|
(provide nest)
|
|
|
|
;; A form that makes it easy to combine many "right-drifting" nested
|
|
;; expressions into a single one, sort of like a generalized version of the `*'
|
|
;; from `let*' and similar forms.
|
|
(define-syntax nest
|
|
(syntax-rules ()
|
|
[(nest () body0 body ...)
|
|
(let () body0 body ...)]
|
|
;; this allows putting definitions in the body
|
|
[(nest ([form forms ...]) body0 body ...)
|
|
(form forms ... (let () body0 body ...))]
|
|
[(nest ([form forms ...] . more) body0 body ...)
|
|
(form forms ... (nest more body0 body ...))]))
|
|
|
|
;; using this instead will allow splicing body expressions in the last form
|
|
;; whatever it happens to be, which can be (ab)used in strange ways
|
|
#;
|
|
(define-syntax nest
|
|
(syntax-rules ()
|
|
[(nest () body ...)
|
|
(begin body ...)]
|
|
[(nest ([form forms ...]) body ...)
|
|
(form forms ... body ...)]
|
|
[(nest ([form forms ...] . more) body ...)
|
|
(form forms ... (nest more body ...))]))
|