2.6 iTunes: "itunes.rkt"
| (require 2htdp/itunes) | package: htdp-lib |
The itunes.rkt teachpack implements and provides the functionality for reading the collection of tracks exported from iTunes.
In iTunes, select Library from the File menu and then choose Export Library. Doing so exports a description of your iTunes collection as a file in XML format.
2.6.1 Data Definitions
struct
(struct track (name artist album time track# added play# played) #:extra-constructor-name make-track) name : string? artist : string? album : string? time : natural-number/c track# : natural-number/c added : date? play# : natural-number/c played : date?
An instance records that the track has title name, is produced by artist, belongs to album, plays for time milliseconds, is positioned at track#, was added at date added, has been played play# times, and was last played at played date.
struct
(struct date (year month day hour minute second) #:extra-constructor-name make-date) year : natural-number/c month : natural-number/c day : natural-number/c hour : natural-number/c minute : natural-number/c second : natural-number/c
An instance records six pieces of information: the date’s year, month (between 1 and 12 inclusive), day (between 1 and 31), hour (between 0 and 23), minute (between 0 and 59), and second (between 0 and 59).
; Track is a track? ; Date is date? ; LTracks is one of: ; – '() ; – (cons Track LTracks) ; LLists is one of: ; – '() ; – (cons LAssoc LLists) ; LAssoc is one of: ; – '() ; – (cons Association LAssoc) ; Association is (cons string? (cons BSDN '())) ; BSDN satisfies either string?, integer?, real?, Date, or boolean?.
2.6.2 Exported Funcions
procedure
(read-itunes-as-lists file-name) → LLists
file-name : string?
Effect reads an XML document from file-name
(read-itunes-as-lists "Library.xml")
procedure
(read-itunes-as-tracks file-name) → LTracks
file-name : string?
Effect reads an XML document from file-name
(read-itunes-as-tracks "Library.xml")
procedure
(create-track name artist album time track# added play# played) → (or/c track? false?) name : string? artist : string? album : string? time : natural-number/c track# : natural-number/c added : date? play# : natural-number/c played : date?
Note This is a checked constructor.
> (create-track "one" "two" "three" 4 5 (create-date 1 2 3 4 5 6) 7 (create-date 1 2 3 4 5 6)) (track "one" "two" "three" 4 5 (date 1 2 3 4 5 6) 7 (date 1 2 3 4 5 6))
> (create-track "one" "two" "three" 4 5 "a date" 7 "another date") #f
procedure
(create-date year month day hour minute second)
→ (or/c date? false?) year : natural-number/c month : natural-number/c day : natural-number/c hour : natural-number/c minute : natural-number/c second : natural-number/c
Note This is a checked constructor.
> (create-date 1 2 3 4 5 6) (date 1 2 3 4 5 6)
> (create-date 1 2 3 "four" 5 6) #f