YURI is a library for safe URI handling. It does not parse URIs; the parsing is done by QURI. What YURI does – all it does – is wrap URIs in an algebraic data type.

YURI is born of bitter experience. In early versions of TBRSS the largest source of run-time errors, by an order of magnitude, was URI parsing. It soon became clear that writing handlers everywhere a URI might be parsed was the wrong approach.

(At the time, I used PURI. QURI is much less finicky, and more careful about what errors it signals, but the argument still stands.)

Instead, by wrapping URIs in an algebraic data type, it becomes possible to safely write functions that parse and access URIs of uncertain provenance without special precautions.

(Although YURI uses an algebraic data type internally, it is not necessary to use pattern matching: ordinary accessors are provided.)

You parse a URI using yuri:uri:

(setq valid (yuri:uri "http://example.com"))
=> (YURI:VALID-URI #<QURI.URI.HTTP:URI-HTTP http://example.com>)

(setq invalid (yuri:uri "http://example.com?á"))
=> (YURI:INVALID-URI "http://example.com?foóbar" #<QURI.ERROR:URI-MALFORMED-STRING>)

(yuri:uri-scheme valid)
=> :http

(yuri:uri-scheme invalid)
=> :http

(yuri:uri->string valid)
=> "http://example.com"

(yuri:uri->string invalid)
=> "http://example.com?á"