88 lines
3.2 KiB
Racket
88 lines
3.2 KiB
Racket
#lang scribble/manual
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@(require scribble/eval
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(for-label (except-in racket/base
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read read-syntax)
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(except-in afl/reader
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read read-syntax)))
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@title{afl}
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@;; example: @racket[(map @#,afl[(+ % 1)] '(1 2 3))]
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@(define-syntax-rule @afl[form ...]
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@elem{@tt{#λ}@racket[form ...]})
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source code: @url["https://github.com/AlexKnauth/afl"]
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@section{#lang afl}
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@defmodulelang[afl]{
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The @racketmodname[afl] language is a meta-language like @racketmodname[at-exp]
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that adds @racketmodname[rackjure]-like anonymous function literals to a language.
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@margin-note{see @secref["func-lit" #:doc '(lib "rackjure/rackjure.scrbl")]}
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For example, @racket[@#,hash-lang[] @#,racketmodname[afl] @#,racketmodname[racket/base]]
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adds anonymous function literals to @racketmodname[racket/base], so that
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@racketmod[afl @#,racketmodname[racket/base]
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(map @#,afl[(+ % 1)] '(1 2 3))]
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produces @racket['(2 3 4)]
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}
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@section{afl/reader}
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@defmodule[afl/reader]
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@deftogether[(@defproc[(afl-read [in input-port? (current-input-port)]
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[#:arg-str arg-str string? (current-arg-string)]) any]{}
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@defproc[(afl-read-syntax [source-name any/c (object-name in)]
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[in input-port? (current-input-port)]
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[#:arg-str arg-str string? (current-arg-string)])
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(or/c syntax? eof-object?)]{})]{
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These procedures implement the @racketmodname[afl] reader. They do so by
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constructing a readtable based on the current one, and using that
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for reading.
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The @racket[arg-str] argument lets you specify something else to use as a placeholder instead of
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@racket[%].
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@examples[
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(require afl/reader)
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(afl-read (open-input-string "#λ(+ % %2)"))
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(afl-read (open-input-string "#λ(+ _ _2)") #:arg-str "_")
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]
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@racketmodname[afl/reader] also exports these functions under the names @racket[read] and
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@racket[read-syntax].
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}
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@defproc[(make-afl-readtable [orig-readtable readtable? (current-readtable)]
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[#:arg-str arg-str string? (current-arg-string)]) readtable?]{
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makes an @racketmodname[afl] readtable based on @racket[orig-readtable].
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The @racket[arg-str] argument lets you specify something else to use as a placeholder instead of
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@racket[%], just like for @racket[afl-read].
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}
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@defproc[(use-afl-readtable [orig-readtable readtable? (current-readtable)]
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[#:arg-str arg-str string? (current-arg-string)]) void?]{
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passes arguments to @racket[make-afl-readtable] and sets the @racket[current-readtable] parameter to
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the resulting readtable.
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It also enables line counting for the @racket[current-input-port] via @racket[port-count-lines!].
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This is mostly useful for the REPL.
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@verbatim{
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Examples:
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> @racket[(require afl/reader)]
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> @racket[(use-afl-readtable)]
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> @racket[(map @#,afl[(+ % %2)] '(1 2 3) '(1 2 3))]
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@racketresult['(2 4 6)]
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> @racket[(use-afl-readtable #:arg-str "_")]
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> @racket[(map @#,afl[(+ _ @#,racketid[__2])] '(1 2 3) '(1 2 3))]
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@racketresult['(2 4 6)]
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}}
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@defparam[current-arg-string arg-str string?]{
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a parameter that controls default values of the @racket[arg-str] arguments to @racket[afl-read] etc.
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} |