Joseph Ferano
a4c6b996ff
The trio the author decided on 2026-09-20 is now all built: def is CL's defparameter — its initialiser runs on every daemon re-run, unguarded, so an edited initialiser repaints the same storage on C-c C-c plus re-run — defonce (Clojure's name for CL's defvar, per the author) initialises once behind the .init~once. flag, and defconst stays the image. One parse arm reads both forms; the difference is Ast.reinit, carried to Tast.global's grerun. Emit.startup_plan gives a def no guard flag, and Check.check_global lifts every def initialiser — zero and literal included — into global/<n>, so the host's startup reaches it through the function cell and a re-evaluated def swaps it (Session's def_inits; Emit.redefinition declares the cell for a non-sibling target). The old defvar spelling is refused with the rename and both compiling spellings, and every program, test, doc and editor list is swept — except sand.flan, the author's live WIP, whose seven defvar lines are flagged in FIX.org and keep its three dependent tests red on this branch.
46 lines
1.7 KiB
Plaintext
46 lines
1.7 KiB
Plaintext
;;;; handler-bind and signal — spec-conditions.md §1 and §2.
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;;;;
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;;;; The accumulation case, which is what makes these two worth having on their
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;;;; own: signal returns (), a handler that returns normally leaves the
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;;;; signalling function to carry on, and with nothing matching signal is a
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;;;; no-op. No control flow is altered, so none of the transfer machinery
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;;;; restart-case needs exists yet.
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(defstruct AssetMissing [id i32])
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(defstruct Corrupt [id i32])
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(defonce seen i64)
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(defonce other i64)
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;;; Signals twice and keeps going both times — that is the whole of §1.
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(defn load-all [] ()
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(signal (AssetMissing {.id 1}))
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(signal (AssetMissing {.id 2}))
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(signal (Corrupt {.id 3})))
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(defn main [] i32
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;; No handler: a no-op, not an abort and not a message (§2).
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(load-all)
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(print seen) (println "") ; 0
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(handler-bind [(AssetMissing [c] (set seen (+ seen (i64 (.id c)))))]
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(load-all))
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(print seen) (println "") ; 1 + 2 = 3
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;; Two clauses, and only the matching one runs for each condition.
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(handler-bind [(AssetMissing [c] (set seen (+ seen 10)))
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(Corrupt [c] (set other (+ other (i64 (.id c)))))]
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(load-all))
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(print seen) (println "") ; 3 + 20 = 23
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(print other) (println "") ; 3
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;; Nesting: the inner frame does not displace the outer one, so both run.
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(handler-bind [(Corrupt [c] (set other (+ other 100)))]
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(handler-bind [(Corrupt [c] (set other (+ other 1000)))]
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(signal (Corrupt {.id 0}))))
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(print other) (println "") ; 3 + 1000 + 100 = 1103
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;; And the stack is back to what it was: no handler, no effect.
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(load-all)
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(print other) (println "") ; 1103
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0)
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