11.2 Syntax Object Content

• a symbol

• a syntax pair (described below)

• the empty list

• an immutable vector containing syntax objects

• an immutable box containing syntax objects

• an immutable hash table containing syntax object values (but not necessarily syntax object keys)

• an immutable prefab structure containing syntax objects

• some other kind of datum—usually a number, boolean, or string

A syntax pair is a pair containing a syntax object as its first element, and either the empty list, a syntax pair, or a syntax object as its second element.

A syntax object that is the result of read-syntax reflects the use of delimited . in the input by creating a syntax object for every pair of parentheses in the source, and by creating a pair-valued syntax object only for parentheses in the source. See Reading Pairs and Lists for more information.

If stx is tainted or armed, then any syntax object in the result of (syntax-e stx) is tainted, and multiple calls to syntax-e may return values that are not eq?. For a stx that is not armed, the results from multiple calls to syntax-e of stx are eq?.

If stx is tainted or armed, then any syntax object in the result of (syntax->list stx) is tainted.

The stripping operation does not mutate stx; it creates new pairs, vectors, boxes, hash tables, and prefab structures as needed to strip lexical and source-location information recursively.

Converted objects in v are given the lexical context information of ctxt and the source-location information of srcloc. If v is not already a syntax object, then the resulting immediate syntax object is given the properties (see Syntax Object Properties) of prop; if v is a pair, vector, box, immutable hash table, or immutable prefab structure, recursively converted values are not given properties or certificates. If ctxt is tainted or armed, then the resulting syntax object from datum->syntax is tainted.

Any of ctxt, srcloc, or prop can be #f, in which case the resulting syntax has no lexical context, source information, and/or new properties.

If srcloc is not #f or a syntax object, it must be a list or vector of five elements:

(list source-name line column position span)

or (vector source-name line column position span)

where source-name-v is an arbitrary value for the source name; line is an integer for the source line, or #f; column is an integer for the source column, or #f; position is an integer for the source position, or #f; and span is an integer for the source span, or #f. The line and column values must both be numbers or both be #f, otherwise the exn:fail:contract exception is raised.

Graph structure is not preserved by the conversion of v to a syntax object. Instead, v is essentially unfolded into a tree. If v has a cycle through pairs, vectors, boxes, immutable hash tables, and immutable prefab structures, then the exn:fail:contract exception is raised.

The ignored argument is allowed for backward compatibility and has no effect on the returned syntax object.

See also quote-syntax/prune.