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This egg provides an interface to the Yelp API. Yelp is a social database of reviews of restaurants and businesses. It also provides generalized lookup by phone number, geocode, or address across the United States, Canada, and Great Britain. All six Yelp APIs are supported along with a simple query mechanism for traversing the JSON query result. A valid Yelp YWSID is required to use this API. There is no charge for a YWSID, though each YWSID has a daily query limit (1000) and use is subject to Yelp's API Terms of Use.

NB: this egg implements the (now) deprecated Yelp v1.0 API.


#;1> (use yelp)
#;2> (set-ywsid! "qvGjCuKXg8adMmACm7haqw")     ;; example YWSID
#;3> (define y (by-phone "4154376800"))
#;4> (display-info y)
Categories: Pizza
Neighborhood: Mission
Pizzeria Delfina
3611 18th Street
San Francisco, CA 94110
37.761398 -122.424003
#;5> (decode y)
  text: OK
  code: 0
  version: 1.1.1
businesses: (1)
  country_code: US
  id: bai6umLcCNy9cXql0Js2RQ
  is_closed: #f
  city: San Francisco
  review_count: 836
  zip: 94110
  state: CA
#;6> (find y "")
#;7> (find y "")
#;8> (find y "")


Derrell Piper


Requires the json and http-client eggs.

In addition, the chicken-install tests require the test egg. -test also requires a valid YWSID exist in ../ywsid above the egg's temporary install directory. When fetched with chicken-install -r, simply creating a file named ywsid in the parent directory (i.e., the one in which you did the chicken-install -r) with the following content:

(set-ywsid! "<your-personal-ywsid-goes-here>")

...and then doing a chicken-install -test in the yelp subdirectory, should work.

None of this matters if you don't care about regression tests or if you do not specify -test to chicken-install.


Authorization and Introspection

[procedure] (set-ywsid! YWSID)

Sets the Yelp web service ID to the value of YWSID. This must be done before calling any other function in this egg.

[procedure] (valid? OBJECT)

Is the OBJECT a valid Yelp response? There's no need to check valid? if you check for 'yelp-success.

All Yelp responses include this structure:

  text: OK
  code: 0
  version: 1.1.1

valid? checks for both "OK" and 0.

Error Handling

The Yelp API consists of the following functions:

Each of these functions returns two values. The first value is a RESPONSE object if successful or a string representing an error code (either from Yelp or internally generated). The second value is a symbolic return status. These values are defined in this egg:

Other values represent the translation of "message.code" in the Yelp response. 'yelp-success implies valid?.

Yelp Phone API

See Yelp Phone API.

[procedure] (by-phone NUMBER)

Look up a business by its phone number, NUMBER.

The following phone syntax is understood:

This egg currently understands only the North American Numbering Plan syntax (US and Canada). Sorry mates.

Yelp Neighborhood API

See Yelp Neighborhood API.

[procedure] (hood-for-address LOCATION #:CC)

Returns the neighborhood name associated with a street address, LOCATION.

[procedure] (hood-for-geocode LAT LON)

Returns the neighborhood name associated with a geocode location, LAT and LON.

Yelp Review Search API

See Yelp Review Search API

[procedure] (near-address TERM LOCATION #:NUMBER #:CC #:CATEGORY)

Returns a list of NUMBER reviews for businesses containing TERM and located near the address LOCATION. The CATEGORY keyword may be used to limit the search to a particular Yelp category name, e.g., "vietnamese".

Yelp's search algorithm is quite liberal in what it accepts for LOCATION; neighborhood names are valid terms as are common abbreviations for major cities. For example:

#;1> (display-info (near-address "tokyo a go-go" "mission sf"))
Categories: Sushi Bars, Japanese
Neighborhood: Mission
Tokyo Go Go
3174 16th Street
Suite 250I
San Francisco, CA 94103
37.764900 -122.424003
#;2> (display-info (near-address "john's pizzeria" "nyc"))
Categories: Pizza
Neighborhood: West Village
John's Pizzeria
278 Bleecker St
New York, NY 10014
40.731712 -74.003274
[procedure] (near-geocode TERM LAT LON #:NUMBER #:RADIUS #:CATEGORY)

Returns a list of NUMBER reviews for businesses containing TERM and located in a circle around the geocode location LAT and LON for a radius of RADIUS. The Yelp API fails to specify the units (assume US statute miles). The CATEGORY keyword may be used to limit the search to a particular Yelp category name, e.g., "pizza".

[procedure] (near-geobox TERM TL-LAT TL-LON BR-LAT BR-LON #:NUMBER #:CATEGORY)

Returns a list of NUMBER reviews for businesses containing TERM and located in a box with the top-left geocode of TL-LAT and TL-LON and a bottom-right geocode of BR-LAT and BR-LON. The CATEGORY keyword may be used to limit the search to a particular Yelp category name, e.g., "divebars+lounges".

Display and Query

[procedure] (display-info RESPONSE [PORT])

Display basic information for a Yelp RESPONSE on PORT. For example:

#;1> (display-info (by-phone "415.673.3163"))
Categories: Vietnamese
Neighborhood: Civic Center/Tenderloin
Pho Tan Hoa
431 Jones St
San Francisco, CA 94102
37.785377 -122.412916
[procedure] (decode RESPONSE [PORT])

Walks the JSON tree and decodes the response to PORT. Primarily useful during development to determine the pathname of interest.

[procedure] (find RESPONSE PATH)

Walks the JSON tree and searches for the JSON key specified by PATH. They syntax of find uses simple dotted notation to describe the pathname, for example: or message.code.

Implementation Notes

The Yelp routines alway return an outermost JSON structure which the JSON egg maps to a vector. find returns a list, vector, or a simple value (number, string, #t, #f, or null), depending on what's being queried. decode and find accept lists and vectors. For example:

#;1> (define y (by-phone "(415)864-2288"))
#;2> (define c (find y "businesses.categories"))
#;3> (find c "name")
"Sushi Bars"
#;4> (find (list-ref c 0) "name")
"Sushi Bars"
#;5> (for-each (lambda (c) (let ((n (find c "name"))) (print n))) c)
Sushi Bars
#;6> (define m (find y "message"))
#;7> (decode m)
text: OK
code: 0
version: 1.1.1
#;8> (find m "text")

The Yelp API defines the following elements as JSON arrays:

Note that find stops on first match, so regular iteration must be used to access second and subsequent elements, as in the first example above (i.e., categories by "name").


The Yelp servers sometime return spurious HTML 301 redirects (on a good day) for no apparent reason. There's a sizeable amount of information returned by default for the "near-" queries, so it makes sense to limit queries using #:number or #:category when possible.

Version History


Copyright (C) 2009 Derrell Piper. BSD-licensed.