57 lines
2.5 KiB
Racket
57 lines
2.5 KiB
Racket
#lang scribble/manual
|
|
@require[@for-label[dotlambda]]
|
|
|
|
@title{Dotted identifiers and @racket[λ<arg>.code] syntax}
|
|
@author[@author+email["Georges Dupéron" "georges.duperon@gmail.com"]]
|
|
|
|
@(begin
|
|
(module orig racket/base
|
|
(require scribble/manual
|
|
typed/racket/base)
|
|
(provide orig:#%module-begin)
|
|
(define orig:#%module-begin (racket #%module-begin)))
|
|
(require 'orig))
|
|
|
|
@defmodulelang[dotlambda]{
|
|
This @hash-lang[] language overrides @orig:#%module-begin from
|
|
@racketmodname[typed/racket/base], and splits identifiers which contain dots,
|
|
following these rules:
|
|
@itemlist[
|
|
@item{A single dot splits the identifier, and the dot is replaced with
|
|
@racket[#%dot-separator]. If an identifier is split by one or more
|
|
non-consecutive dots, all the resulting identifiers, including the
|
|
occurrences @racket[#%dot-separator] are placed in a syntax list, starting
|
|
with @racket[#%dotted-id], so that @racket[a.b.c] gets transformed into
|
|
@racket[(#%dotted-id a #%dot-separator b #%dot-separator c)].}
|
|
@item{A leading dot (which is not followed by another dot) is allowed, and is
|
|
replaced with @racket[#%dot-separator], like dots occurring in the middle of
|
|
the identifier.}
|
|
@item{A dot immediately preceded or followed by an ellipsis @racket[…] can be
|
|
omitted, so that @racket[a.….b], @racket[a….b], @racket[a.…b] and
|
|
@racket[a…b] are all translated to
|
|
@racket[(#%dotted-id a #%dot-separator … #%dot-separator b)].}
|
|
@item{Two or more dots do not split the identifier, but one of the dots is
|
|
removed (i.e. it escapes the other dots).}
|
|
@item{If an identifier ends with a dot, a single trailing dot is removed and
|
|
the identifier is otherwise left intact (i.e. the trailing dot escapes the
|
|
whole identifier).}
|
|
@item{Identifiers consisting only of dots are left unchanged, as well as the
|
|
following: @racket[..+], @racket[...+], @racket[..*], @racket[...*],
|
|
@racket[…], @racket[…+], @racket[…*] and @racket[::...].}]
|
|
|
|
Furthermore the syntax @racket[λvar.(expr …)] is recognised as a shorthand for
|
|
@racket[(λ (var) (expr …))], so that @racket[λx.(+ x 2)] is translated to
|
|
@racket[(λ (x) (+ x 2))]. If the @racket[_var] part is left empty, then it
|
|
defaults to @racket[%], so that @racket[λ.(+ % 2)] is translated to
|
|
@racket[(λ (%) (+ % 2))].}
|
|
|
|
@section{Module language for @racket[dotlambda]}
|
|
|
|
@defmodulelang[dotlambda/lang]{
|
|
This language is equivalent to
|
|
@racket[#,(hash-lang) #,(racketmodname dotlambda)], but can also be used as
|
|
a module language.
|
|
}
|
|
|
|
|