13.10 Fast-Load Serialization
|(require racket/fasl)||package: base|
(s-exp->fasl v [ out #:keep-mutable? keep-mutable? #:handle-fail handle-fail #:external-lift? external-lift? #:skip-prefix? skip-prefix?]) → (or/c (void) bytes?) v : any/c out : (or/c output-port? #f) = #f keep-mutable? : any/c = #f handle-fail : (or/c #f (any/c . -> . any/c)) = #f external-lift? : (or/c #f (any/c . -> . any/c)) = #f skip-prefix? : any/c = #f
(fasl->s-exp in [ #:datum-intern? datum-intern? #:external-lifts external-lifts #:skip-prefix? skip-prefix?]) → any/c in : (or/c input-port? bytes?) datum-intern? : any/c = #t external-lifts : vector? = '#() skip-prefix? : any/c = #f
The v argument must be a value that could be quoted
as a literal—
If a value within v is not valid as a quoted literal, and if handle-fail is not #f, then handle-fail is called on the nested value, and the result of handle-fail is written in that value’s place. The handle-fail procedure might raise an exception instead of returning a replacement value. If handle-fail is #f, then the exn:fail:contract exception is raised when an invalid value is encountered.
If external-lift? is not #f, then it receives each value v-sub encountered in v by s-exp->fasl. If the result of external-lift? on v-sub is true, then v-sub is not encoded in the result, and it instead treated as externally lifted. A deserializing fasl->s-exp receives a external-lifts vector that has one value for each externally lifted value, in the same order as passed to external-lift? on serialization.
Like (compile `',v), s-exp->fasl does not preserve graph structure, support cycles, or handle non-prefab structures. Compose s-exp->fasl with serialize to preserve graph structure, handle cyclic data, and encode serializable structures. The s-exp->fasl and fasl->s-exp functions consult current-write-relative-directory and current-load-relative-directory (falling back to current-directory), respectively, in the same way as bytecode saving and loading to store paths in relative form, and they similarly allow and convert constrained srcloc values (see Printing Compiled Code).
Unless keep-mutable? is provided as true to s-exp->fasl, then mutable values in v are replaced by immutable values when the result is decoded by fasl->s-exp. Unless datum-intern? is provided as #f, then any immutable value produced by fasl->s-exp is filtered by datum-intern-literal. The defaults make the composition of s-exp->fasl and fasl->s-exp behave like the composition of write and read.
If skip-prefix? is not #f, then a prefix that identifies the stream as a serialization is not written by s-exp->fasl or read by fasl->s-exp. Omitting a prefix can save a small amount of space, which can useful when serializing small values, but it gives up a sanity check on the fasl->s-exp that is often useful.
The byte-string encoding produced by s-exp->fasl is independent of the Racket version, except as future Racket versions introduce extensions that are not currently recognized. In particular, the result of s-exp->fasl will be valid as input to any future version of fasl->s-exp (as long as the skip-prefix? arguments are consistent).
> (define fasl (s-exp->fasl (list #("speed") 'racer #\!))) > fasl
> (fasl->s-exp fasl)
'(#("speed") racer #\!)
Changed in version 184.108.40.206 of package base: Made s-exp->fasl format version-independent
and added the #:keep-mutable?
and #:datum-intern? arguments.
Changed in version 220.127.116.11: Added support for correlated objects.
Changed in version 18.104.22.168: Added the #:handle-fail argument.
Changed in version 22.214.171.124: Added the #:external-lift? and #:external-lifts arguments.
Changed in version 126.96.36.199: Added support for fxvectors and flvectors.