2 ms·

How do Lisp developers deal with XML and JSON? Convert it to s-expressions. As a common lisp developer, that is only very vaguely true for me. The mapping I p

by aidenn0 6mo ago

How do Lisp developers deal with XML and JSON? Convert it to s-expressions. As a common lisp developer, that is only very vaguely true for me. The mapping I prefer for json<->Lisp is: true: t false: nil null: :null [] #() {} (make-hash-table :test #'equal) This falls out of my desire for the mapping to be bijective: - The only built-in type that is unambiguously a mapping type is hash-tabe. - nil is the only value that is falsy in CL - () is the same as nil, so we can't use it as an empty list; vectors are the obvious alternative - Not really any obvious values left to use for "null" so punt to a keyword.

sparkie 6mo ago
In Kernel I would use something like this: true #t false #f null () [...] (& ...) "k" : v (: k v) {...} (@ ...) Where &, :, @ are defined as: ($define! & ($lambda args (cons list args))) ($define! : ($vau (key value) env (list key (eval value env)))) ($define! @ (wrap ($vau kvpairs env (eval (list* $bindings->environment kvpairs) env)))) Using the "person" example from the JSON/syntax section on Wikipedia: ($define! person (@ (: first_name "John") (: last_name "Smith") (: is_alive #t) (: age 27) (: address (@ (: street_address "21 2nd Street") (: city "New York") (: state "NY") (: postal_code "10021-3100"))) (: phone_numbers (& (@ (: type "home") (: number "212 555-1234")) (@ (: type "office") (: number "646 555-4567")))) (: children (& "Catherine" "Thomas" "Trevor")) (: spouse ()))) I would then define `?` ($define! ? $remote-eval) Now we can query the object. > (? age person) 27 > (? postal_code (? address person)) "10021-3100" > (car (? children person)) "Catherine" > (cdr (? children person)) ("Thomas" "Trevor") > (? type (cadr (? phone_numbers person))) "office" > (? number (car (? phone_numbers person))) "212 555-1234" > ($define! full_name ($lambda (p) (string-append (? first_name p) " " (? last_name p)))) > (full_name person) "John Smith"
- anonzzzies 6mo ago
  [0] https://web.cs.wpi.edu/~jshutt/kernel.html https://web.cs.wpi.edu/~jshutt/kernel.html
- aidenn0 6mo ago
  I don't know kernel very well; what will the value of person print as?
  - sparkie 6mo ago
    There's no "external representation" for environments. In klisp it will just print: [#environment] The environment type is encapsulated, so it doesn't give you very useful debug information. Perhaps having `@` produce an environment is the wrong approach and we should just produce an association list instead - then move `$bindings->environment` into the `?` operative to enable querying.
lgrapenthin 6mo ago
In Clojure true: true false: false null: nil []: [] {}: {}

by aidenn0 6mo ago

sparkie 6mo ago

In Kernel I would use something like this: true #t false #f null () [...] (& ...) "k" : v (: k v) {...} (@ ...) Where &, :, @ are defined as: ($define! & ($lambda args (cons list args))) ($define! : ($vau (key value) env (list key (eval value env)))) ($define! @ (wrap ($vau kvpairs env (eval (list* $bindings->environment kvpairs) env)))) Using the "person" example from the JSON/syntax section on Wikipedia: ($define! person (@ (: first_name "John") (: last_name "Smith") (: is_alive #t) (: age 27) (: address (@ (: street_address "21 2nd Street") (: city "New York") (: state "NY") (: postal_code "10021-3100"))) (: phone_numbers (& (@ (: type "home") (: number "212 555-1234")) (@ (: type "office") (: number "646 555-4567")))) (: children (& "Catherine" "Thomas" "Trevor")) (: spouse ()))) I would then define `?` ($define! ? $remote-eval) Now we can query the object. > (? age person) 27 > (? postal_code (? address person)) "10021-3100" > (car (? children person)) "Catherine" > (cdr (? children person)) ("Thomas" "Trevor") > (? type (cadr (? phone_numbers person))) "office" > (? number (car (? phone_numbers person))) "212 555-1234" > ($define! full_name ($lambda (p) (string-append (? first_name p) " " (? last_name p)))) > (full_name person) "John Smith"

anonzzzies 6mo ago
[0] https://web.cs.wpi.edu/~jshutt/kernel.html https://web.cs.wpi.edu/~jshutt/kernel.html
aidenn0 6mo ago
I don't know kernel very well; what will the value of person print as?
- sparkie 6mo ago
  There's no "external representation" for environments. In klisp it will just print: [#environment] The environment type is encapsulated, so it doesn't give you very useful debug information. Perhaps having `@` produce an environment is the wrong approach and we should just produce an association list instead - then move `$bindings->environment` into the `?` operative to enable querying.

lgrapenthin 6mo ago

In Clojure true: true false: false null: nil []: [] {}: {}