urbit/pkg/arvo/ted/example-fetch.hoon
2019-11-16 04:07:09 -08:00

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:: Little app to demonstrate the structure of threads.
::
:: Fetches the top comment of each of the top stories from Hacker News
::
::
/- spider
/+ *strandio
=, strand=strand:spider
|%
+$ top-comments (list tape)
--
=; core
^- thread:spider
|= vase
=/ m (strand ,vase)
^- form:m
~& > 'entering main loop'
;< ~ bind:m
%- (main-loop ,top-comments)
:~ handle-print:core
handle-fetch:core
:: `$-(top-comments _*form:(strand ,top-comments))`handle-poll:core
==
(pure:m *vase)
|%
:: Helper function to print a comment
::
++ comment-to-tang
|= =tape
^- tang
%+ welp
%+ turn (rip 10 (crip tape))
|= line=cord
leaf+(trip line)
[leaf+""]~
::
:: All the URLs we fetch from
::
++ urls
=/ base "https://hacker-news.firebaseio.com/v0/"
:* top-stories=(weld base "topstories.json")
item=|=(item=@ud `tape`:(welp base "item/" +>:(scow %ui item) ".json"))
==
::
:: XX
::
++ handle-print
|= =top-comments
=/ m (strand ,^top-comments)
^- form:m
;< =vase bind:m ((handle ,vase) (take-poke %example-fetch-print))
(print top-comments)
::
:: XX
::
++ print
|= =top-comments
=/ m (strand ,^top-comments)
^- form:m
%- (slog leaf+"drumroll please..." ~)
;< ~ bind:m (sleep ~s3)
%- (slog leaf+"Top comments:" (zing (turn top-comments comment-to-tang)))
(pure:m top-comments)
::
:: XX
::
++ handle-fetch
|= =top-comments
=/ m (strand ,^top-comments)
^- form:m
;< =vase bind:m ((handle ,vase) (take-poke %example-fetch-fetch))
(fetch top-comments)
::
:: XX
::
++ fetch
|= =top-comments
=/ m (strand ,^top-comments)
^- form:m
=. top-comments ~
%+ (set-timeout ^top-comments) ~s15
;< =top-stories=json bind:m (fetch-json top-stories:urls)
=/ top-stories=(list @ud)
((ar ni):dejs:format top-stories-json)
::
:: Loop through the first 5 stories
::
=. top-stories (scag 5 top-stories)
|- ^- form:m
=* loop $
::
:: If done, tell subscribers and print the results
::
?~ top-stories
(print top-comments)
::
:: Else, fetch the story info
::
%- (slog leaf+"fetching item #{+>:(scow %ui i.top-stories)}" ~)
;< =story-info=json bind:m (fetch-json (item:urls i.top-stories))
=/ story-comments=(unit (list @ud))
((ot kids+(ar ni) ~):dejs-soft:format story-info-json)
::
:: If no comments, say so
::
?: |(?=(~ story-comments) ?=(~ u.story-comments))
=. top-comments ["<no top comment>" top-comments]
loop(top-stories t.top-stories)
::
:: Else, fetch comment info
::
;< =comment-info=json bind:m (fetch-json (item:urls i.u.story-comments))
=/ comment-text=(unit tape)
((ot text+sa ~):dejs-soft:format comment-info-json)
::
:: If no text (eg comment deleted), record that
::
?~ comment-text
=. top-comments ["<top comment has no text>" top-comments]
loop(top-stories t.top-stories)
::
:: Else, add text to state
::
=. top-comments [u.comment-text top-comments]
loop(top-stories t.top-stories)
::
:: XX
::
++ handle-poll
|= =top-comments
=/ m (strand ,^top-comments)
^- form:m
!!
--