Shangri-La Shangri-La Shangri-La is a fictional place described in the 1933 novel "Lost Horizon" by British author James Hilton. Hilton describes Shangri-La as a mystical, harmonious valley, gently guided from a lamasery, enclosed in the western end of the Kunlun Mountains. Shangri-La has become synonymous with any earthly paradise, particularly a mythical Himalayan utopia – a permanently happy land, isolated from the world. In the novel, the people who live at Shangri-La are almost immortal, living hundreds of years beyond the normal lifespan and only very slowly aging in appearance. The name also evokes the imagery of the exoticism of the
S-expression be formatted as pretty printed S-expressions using the function PPRINT (note: with two Ps, short for "pretty"-print). Lisp programs are valid s-expressions, but not all s-expressions are valid Lisp programs. codice_21 is a valid s-expression, but not a valid Lisp program, since Lisp uses prefix notation and a floating point number (here 1.0) is not valid as an operation (the first element of the expression). An S-expression preceded by a single quotation mark, as in codice_22, is syntactic sugar for a quoted S-expression, in this case codice_23. S-Expressions are often compared to XML, a key difference being that S-Expressions are