Hi All,
The example program below defines a macro, my-let, that
enables you to write let-bindings with / as a separator.
(my-let (x = 1 / y = 2 / z = 3)
(+ x y z))
I'd like to improve the definition of the syntax class called bindings.
Ideally I'd like to replace its definition with:
(begin-for-syntax
(define-splicing-syntax-class bindings
[pattern (~separated / b:binding)
#:with names #'(b.name ...)
#:with expressions #'(b.expression ...)]))
But how can I define the fictitious ~separated ?
/Jens Axel
#lang racket
(require (for-syntax syntax/parse))
(begin-for-syntax
(define-splicing-syntax-class binding #:literals (=)
[pattern (~seq name:id = expression:expr)])
(define-splicing-syntax-class bindings
[pattern ()
#:with names #'()
#:with expressions #'()]
[pattern (b:binding)
#:with names #'(b.name)
#:with expressions #'(b.expression)]
[pattern (b:binding (~seq / b*:binding) ...)
#:with names #'(b.name b*.name ...)
#:with expressions #'(b.expression b*.expression ...)]))
(define-syntax (my-let stx)
(syntax-parse stx
[(_ bs:bindings body)
(with-syntax ([(name ...) #'bs.names]
[(expr ...) #'bs.expressions])
#'(let ([name expr] ...)
body))]))
(my-let (x = 1 / y = 2 / z = 3)
(+ x y z))
--
Jens Axel Søgaard
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