Joseph Ferano
e03028819c
The author's rule: "allow shadowing but warn". A user (defn get ...) is legal, the user's definition wins at every call site in the file that wrote it, and the compiler warns once at the definition. Builtin-wins was never a rule anybody wrote: named_call is one match on the name, the builtin arms are string literals, and the three arms that look a name up are the last three in it. So a guard goes first, the trailing three are factored into ordinary_call, and both routes into it resolve a name the same way. The shadow stops at the file that declared it. An imported package's names were qualified at the import, so a get written inside one is the builtin's and stays the builtin's; the prelude is excluded by its file for the same reason. programs/shadow-builtin.flan is both halves at once. The warning prints from build_program, which is what every command and the dev daemon's reload go through, in the shape --warn-memory established: file:line:col, the squiggle, and an exit status that does not move. And the message that described the old world is gone — the builtin-arity note said a defn does not replace a builtin, which is no longer true and is no longer reachable.
25 lines
997 B
Plaintext
25 lines
997 B
Plaintext
;;;; A defn named after a builtin, and what the name means afterwards.
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;;;;
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;;;; "Allow shadowing but warn": this file's (defn get ...) is legal, it wins
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;;;; at every call site in this file, and the compiler says so once at the
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;;;; definition — the warning is on stderr and the exit status does not move.
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;;;;
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;;;; Two calls, and between them the whole rule:
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;;;;
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;;;; - (get p) is one argument, which the builtin get does not take. It
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;;;; compiles, and it prints the field, because the name resolves to the
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;;;; definition below and the builtin is not consulted about its arity.
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;;;; - (shadowed/field m) reaches into the imported package, whose body calls
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;;;; the builtin get on a dyn map. The shadow does not follow it there: a
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;;;; package's own calls mean what they meant when the package was written.
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(import shadowed "pkgs/shadowed")
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(defstruct P [x i32])
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(defn get [p P] i32 (.x p))
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(defn main [] ()
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(println (get (P {.x 7})))
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(println (shadowed/field {:a 1 :b 4})))
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