Joseph Ferano
ed8dbbcd62
The first is CLHS 9.1.4.1: a clause that signalled the condition it handles used to re-enter itself until the stack ran out. The stale list now names a lifted clause by the function it is written in, and BUILT.md's cost line is measured against master.
47 lines
1.4 KiB
Plaintext
47 lines
1.4 KiB
Plaintext
;;;; A handler-bind clause that signals the condition it is handling.
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;;;;
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;;;; While a clause runs, the handlers in force are the ones that were in force
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;;;; when its handler-bind was established (CLHS 9.1.4.1). So the inner clause's
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;;;; own bad index reaches the *outer* clause, once, and not the inner one
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;;;; again — which used to recurse until the stack ran out.
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;;;;
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;;;; The second half is the other order: after the inner clause has run and
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;;;; declined, the handler it belongs to is in force again for the next signal.
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(defonce hits i64)
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(def grid [4 i32] [1 2 3 4])
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(defn bad [i i32] i32 (at grid i))
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(defn nested [] i64
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(restart-case
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(handler-bind [(BoundsError [c] (set hits (+ hits 100)) (invoke-restart 'outer))]
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(restart-case
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(handler-bind [(BoundsError [c]
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(set hits (+ hits 1))
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(bad 9)
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(invoke-restart 'inner))]
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(bad 7))
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(inner [] 0)))
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(outer [] 0))
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hits)
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(defn again [] i64
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(set hits 0)
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(restart-case
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(handler-bind [(BoundsError [c] (set hits (+ hits 1)) (invoke-restart 'out))]
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(handler-bind [(BoundsError [c] (set hits (+ hits 10)))]
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(bad 5)
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0))
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(out [] 0))
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(restart-case
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(handler-bind [(BoundsError [c] (set hits (+ hits 1000)) (invoke-restart 'out))]
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(bad 6))
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(out [] 0))
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hits)
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(defn main [] i32
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(println (nested))
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(println (again))
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0)
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