45 lines
1.5 KiB
Plaintext
45 lines
1.5 KiB
Plaintext
;;;; A program that stops, for driving the break loop from an editor.
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;;;;
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;;;; It errors on its first frame, with nothing having handled the condition,
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;;;; so [flan dev] meets a program that is already stopped — which is the state
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;;;; an editor has to cope with, and the one that is hardest to arrange on
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;;;; purpose later. Two restarts are on offer and they return different values,
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;;;; so the transcript says which one was chosen.
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;;;;
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;;;; After resuming it keeps polling, because the claim worth testing is that
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;;;; everything else still works on either side of a break.
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(import agent "vendor:agent")
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(defstruct Missing [id i32])
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(defn fetch [n i32] i32
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(restart-case
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(do (error (Missing {.id n})) 0)
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(use-placeholder [] :report "Answer -1" -1)
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(retry [] 7)))
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(defonce ticks i64)
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(defn step [] i64
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(set ticks (+ ticks 1))
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ticks)
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;;; A division under a restart-case, called from the editor rather than from
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;;; main. It is here for the *other* condition the runtime builds by hand:
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;;; ArithError's three fields are a C struct in flan_rt.c and a defstruct in
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;;; the prelude, and the break loop's render now reads them field by field,
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;;; padding and all. A layout that drifted would show the op in `lhs'.
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;;; The operands are parameters so nothing constant-folds the division away.
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(defn divide [a i64 b i64] i64
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(restart-case
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(/ a b)
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(use-zero [] 0)))
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(defn main [] i32
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(agent/start "/tmp/flan-dev-break-fallback.sock")
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(print (fetch 1)) (println "")
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(dotimes [i 4000]
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(agent/wait 5)
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(set ticks (step)))
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0)
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