Here's a list of the features provided by different kinds of standard record systems. The specific syntax of syntax forms and the exact calling conventions of procedures is ignored here.

Glossary:

• A record constructor is a procedure that constructs a record of a specified type
• A record accessor is a procedure that gets the value of a particular element of a record
• A record mutator is a procedure that sets the value of a particular element of a record
• A record predicate is a procedure that returns #t or #f depending on whether its argument is an instance of a given record type

• An RTD (record-type-descriptor) is a run-time object representing a record type

Features:

• [SyntacticRecords Syntactic] means record types are specified by one or more macros that bind identifiers to record types, constructors, accessors, mutators, and predicates.
• ''Procedural'' means that record types are created by a procedure which returns an RTD, and that by applying other procedures to the RTD, constructors, accessors, mutators, and predicates are returned

• [GenerativeRecords Generative] record types are unique in each definition
• [NonGenerativeRecords Non-generative] record types have a uid (a symbol) and are identical if they share the same symbol

• ''Opaque''
• ''Translucent''

• A ''natural constructor'' is a procedure whose arguments correspond to the fields of the record in the order they were specified when creating the RTD
• A ''filtering constructor'' is a procedure whose arguments correspond to some of the fields of the record in an order which may or may not be the specification order.
• A ''generalized constructor'' is one which applies an arbitrary procedure, called the protocol procedure, that transforms its arguments in any way desired and then calls a natural constructor.
• A ''label constructor'' is one which maps field labels to values independent of order.

Standards

(srfi 9) is syntactic. It provides:

• Distinct types
• Opaque RTD objects
• A single filtering constructor
• Mutable fields
• Immutable fields
• Generative records
• Top-level definitions only

(srfi 57) is syntactic. It extends (srfi 9) as follows:

• Multiple interface inheritance
• A label constructor
• Record composition
• Functional record update
• In-place record update

(srfi 99 records syntactic) is syntactic. It extends (srfi 9) as follows:

• Record definitions appear where other definitions appear
• Single inheritance
• Natural constructor
• Auto-generated non-hygienic names

(rnrs records syntactic 6) is syntactic. It extends (srfi 99 records syntactic) as follows:

• Generalized constructor
• Sealed RTDs from which other RTDs cannot inherit (optional in SRFI-99)
• Opaque RTDs that create records that don't satisfy RECORD? (optional in SRFI-99)
• Non-generative RTDs (optional in SRFI-99)

(rnrs records procedural 6) is procedural. It extends (srfi 99 records syntactic) as follows:

• RTDs have names (symbols)
• Procedure to create an RTD
• Procedure to create natural and filtering constructors from an RTD
• Procedure to create predicates from an RTD
• Procedure to create accessors and mutators from an RTD and a field name

(srfi 99 records inspection) is procedural. It provides the following:

• Predicate that returns #t on any record
• Procedure to extract RTD from a record
• Procedures to access name, parent, field names, inherited field names from an RTD

(rnrs records procedural 6) is procedural. It extends (rnrs records syntactic 6) as follows:

• Procedure to create an RTD
• Procedure to create a constructor-descriptor (which can then create a constructor) for natural and generalized constructors from an RTD
• Procedure to create predicates from an RTD
• Procedure to create accessors and mutators from an RTD and a field index (doesn't work for inherited fields)

(rnrs records inspection 6) is procedural. It extends (srfi 99 records inspection) as follows:

• Procedures to extract sealedness, opaqueness, and nongenerative id from an RTD; these are optional in SRFI-99

Issues and Discussions

• EfficiencyConcerns
• InterfaceComparison

Eventually there should be a companion page for native record systems provided by individual Schemes.