suzanne.soy/beautiful-racket
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

tweak

Browse Source
This commit is contained in:
Matthew Butterick 2016-03-20 09:22:49 -07:00
parent b7286f208c
commit 7dd003deff
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
br/eopl.rkt
View File

@ -31,8 +31,8 @@
(define #'(define-datatype <base-type> <base-type-predicate?>
(<subtype> [<field> <field-predicate?>] ...) ...)
#'(begin
(struct <base-type> () #:transparent)
(struct <subtype> <base-type> (<field> ...) #:transparent
(struct <base-type> () #:transparent #:mutable)
(struct <subtype> <base-type> (<field> ...) #:transparent #:mutable
#:guard (λ(<field> ... name)
(unless (<field-predicate?> <field>)
(error name (format "arg ~a is not ~a" <field> '<field-predicate?>))) ...