Joseph Ferano
c604911ecb
Loading a package kept one table, keyed by real path, and used it for two different questions. Already loaded meant "skip", which is right for the second route of a diamond and wrong for a ring: a package that imported itself round a chain met its own entry, contributed nothing, and appeared to work. The comment said so and called it a feature. It is not one. A ring has no package order, and a definite package order is what the macro expander needs — every defmacro has to be compiled before anything that calls it. So the chain currently being read is now carried separately from the set already finished. A directory found in the first is a cycle and is refused; a directory found only in the second is still the diamond's second route and still a no-op. The refusal names the ring — a -> b -> c -> a — and only the ring, not the route that led to it. "There is a cycle" leaves the reader to find which three imports it was. pkgs now comes back dependencies-first, which is the topological order the acyclic rule buys. The declaration list is left alone: check.ml collects every top-level name before it checks any body, so declarations are order-independent by construction and sorting them would be churn in the field every test reads. The tests are a real tree rather than a second copy of pkg-shared. pkg-diamond builds a shape/Box inside area/ and hands it to a function declared inside draw/, which only type-checks if the bottom package was read once — two copies of one struct are two types. What proves it is the numbers, not the compile.
16 lines
746 B
Plaintext
16 lines
746 B
Plaintext
;;;; One directory, two names — where one of the two is a package's.
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;;;;
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;;;; pkg-two-aliases.flan has both import forms in the entry file, where the
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;;;; clash is written down in one place and easy to see. This is the case that
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;;;; only exists once a package may import a package: area/ imports shape as
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;;;; [shape], this file imports the same directory as [sh], and the two names
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;;;; are pages apart. The rule is the same one — a directory reached twice
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;;;; arrives under one set of names, or every declaration in it exists twice —
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;;;; and it has to hold through a chain, because that is where nobody can see
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;;;; both halves at once.
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(import sh "pkgs/shape")
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(import area "pkgs/area")
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(defn main [] i32 (area/of (sh/box 2 2)))
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