Joseph Ferano
96ab4c9cf0
print-str, print-i64, print-f64, print-bytes, print-line and newline leave the prelude. print and println are the whole printing surface now, and print is the better call at every one of the sites that used them: it is the same structural walk without the newline, so the no-newline case the family was kept for is covered, and it takes the value as it is. The old print-i64 forced an explicit (i64 x) at every call site, because this language widens nothing implicitly; that cast is gone from 127 places. Dropping it moves one answer. hash-grid returns u64, and the cast through the signed printer showed sand-headless's hash as -2851001042534928384. print routes a u64 through flan_u64_to_bytes, so it now prints 15595743031174623232 — the same 64 bits, read as the unsigned number they are. The pinned expectation follows the correction. test-flan-dev.el and test_session.ml both reached for print-line as "a name the prelude has"; they reach for rand-seed instead.
81 lines
3.3 KiB
Plaintext
81 lines
3.3 KiB
Plaintext
;;;; restart-case and invoke-restart — spec-conditions.md §3 to §6.
|
|
;;;;
|
|
;;;; The transfer. A handler runs where the signal was, decides, and control
|
|
;;;; resumes at a restart-case further out: every function in between returns
|
|
;;;; early with the target in the channel, running its defers on the way (§5).
|
|
;;;; Restarts take no parameters in this version.
|
|
(defstruct AssetMissing [id i32])
|
|
|
|
(defvar log i64)
|
|
|
|
;;; The signalling end. Two frames below the restart-case, so the transfer has
|
|
;;; something to cross.
|
|
(defn load [n i32] i32
|
|
(signal (AssetMissing {:id n}))
|
|
100)
|
|
|
|
;;; §5: this defer runs whether the call below returns or transfers, and it
|
|
;;; runs before the clause body starts.
|
|
(defn middle [n i32] i32
|
|
(defer (set log (+ log 1)))
|
|
(+ (load n) 1))
|
|
|
|
;;; The spec's load-texture shape (§1): a restart-case in value position, whose
|
|
;;; fall-through has to produce the type too.
|
|
(defn fetch [n i32] i32
|
|
(restart-case (middle n)
|
|
(use-placeholder [] -1)
|
|
(retry [] 7)))
|
|
|
|
;;; §4: an inner restart-case shadows an outer one offering the same name, and
|
|
;;; the outer one is reached again once the inner has been left.
|
|
(defn nested [n i32] i32
|
|
(restart-case
|
|
(+ (restart-case (middle n)
|
|
(use-placeholder [] 10))
|
|
1000)
|
|
(use-placeholder [] 20)))
|
|
|
|
;;; §2's diverging variant. Same lookup, but a handler that returns normally
|
|
;;; has not answered it: only a transfer gets past, so the fall-through the
|
|
;;; signalling version needs does not exist here.
|
|
(defn strict [n i32] i32
|
|
(restart-case
|
|
(do (error (AssetMissing {:id n}))
|
|
;; unreachable — error is Never, so nothing after it runs
|
|
0)
|
|
(use-placeholder [] -2)))
|
|
|
|
(defn main [] i32
|
|
;; Nothing handles it, so signal is a no-op and the body's own value stands.
|
|
(print (fetch 1)) (println "") ; 101
|
|
(print log) (println "") ; 1
|
|
|
|
;; A handler that transfers: the clause's value is the restart-case's.
|
|
(handler-bind [(AssetMissing [c] (invoke-restart 'use-placeholder))]
|
|
(print (fetch 2)) (println "")) ; -1
|
|
(print log) (println "") ; 2 — the defer ran
|
|
|
|
(handler-bind [(AssetMissing [c] (invoke-restart 'retry))]
|
|
(print (fetch 3)) (println "")) ; 7
|
|
|
|
;; §4: the innermost frame offering the name wins, and the clause yields to
|
|
;; *its* own continuation — so the +1000 written around the inner
|
|
;; restart-case still runs, and the outer clause never does.
|
|
(handler-bind [(AssetMissing [c] (invoke-restart 'use-placeholder))]
|
|
(print (nested 4)) (println "")) ; 1010
|
|
|
|
;; A handler that returns normally transfers nothing: §1's accumulation case
|
|
;; still works, and the fall-through stands.
|
|
(handler-bind [(AssetMissing [c] (set log (+ log 100)))]
|
|
(print (fetch 5)) (println "")) ; 101
|
|
;; The handler runs at the signal, which is inside the call the defer
|
|
;; belongs to, so its +100 lands before that defer's +1.
|
|
(print log) (println "") ; 4 + 100 + 1 = 105
|
|
|
|
;; error, answered by a transfer. Unanswered it stops the program, which is
|
|
;; the trap case in the acceptance table rather than a line here.
|
|
(handler-bind [(AssetMissing [c] (invoke-restart 'use-placeholder))]
|
|
(print (strict 6)) (println "")) ; -2
|
|
0)
|