chemical-compounds -- parsing, pretty-printing, and formula weights of chemical compounds. Copyright 2004 Peter Scott Released under the LLGPL (see http://opensource.franz.com/preamble.html). Introduction ============ Sometimes you want to be able to parse chemical formulas in a normal, user-friendly syntax. For example, water is usually written "H2O". This representation is good for users, but for Lisp code, you need a different representation. In chemical-compounds, H2O would be represented as ((H 2) O). A more complicated molecule is glucose, C6H12O6. This is ((C 6) (H 12) (O 6)) in our internal representation. You may have noticed that "C6H12O6" is ugly and hard to read, due to the clunky way that plain text deals with the subscripts. Therefore, in the format used by chemical-compounds, glucose is "C6 H12 O6", with spaces. Some chemical formulas parenthesize parts of the compound and add a subscript. The formula "(C O2)4 H2" would be parsed as (((C (O 2)) 4) (H 2)). Functions ========= The :compounds package exports four functions: (pprint-compound compound stream): takes a compound in the Lisp internal representation and prints it to a stream in the pretty syntax. Example: (with-output-to-string (s) (pprint-compound '((H 2) O) s)) => "H2 O" ----------- (parse-compound string): parse a compound string and return the internal Lisp representation of it. Examples: (parse-compound "C6 H12 O6") => ((C 6) (H 12) (O 6)) (parse-compound "(C O2)4 H2") => (((C (O 2)) 4) (H 2)) ----------- (formula-weight compound): Calculate the number of grams per mole of a compound. Examples: (formula-weight '((C 6) (H 12) (O 6))) => 180.15768 (formula-weight (parse-compound "C6 H12 O6")) => 180.15768 ----------- (get-compound compound): Return a compound designator given either a compound designator or a string in compound syntax. Examples: (get-compound "C6 H12 O6") => ((C 6) (H 12) (O 6)) (get-compound '((C 6) (H 12) (O 6))) => ((C 6) (H 12) (O 6)) ----------- If you have any questions, please ask them on the chemboy-devel mailing list at <chemboy-devel@common-lisp.net>.