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.
13 lines
501 B
Plaintext
13 lines
501 B
Plaintext
;;;; The bottom of the diamond: the one package both middles depend on.
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;;;;
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;;;; Box has to be one type. If this directory were read twice — once along
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;;;; area/, once along draw/ — there would be two defstructs both qualified
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;;;; shape/Box, and the checker would either refuse the collision or, worse,
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;;;; unify nothing. That is the failure this tree exists to catch.
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(defstruct Box [w i32 h i32])
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(defn box [w i32 h i32] Box (Box {.w w .h h}))
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(defn wide? [b Box] bool (> (.w b) (.h b)))
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