d4dca3baac
This adds a `test_extern` command. Usage: ``` import Lean.Util.TestExtern test_extern Nat.add 17 37 ``` This: * Checks that the head symbol has an `@[extern]` attribute. * Writes down `t == t'`, where `t` is the term provided, and `t'` is the reference implementation (specifically, `t` with the head symbol unfolded). * Tries to reduce this to `true`, and complains if this fails. Note that the type of the term must have a `BEq` instance for this to work: there's a self-explanatory error message if it isn't available.
7 lines
203 B
Text
7 lines
203 B
Text
error: stdout:
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./././TestExtern.lean:5:0: error: native implementation did not agree with reference implementation!
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Compare the outputs of:
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#eval Nat.not_add 4 5
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and
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#eval match 4, 5 with
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| x, x_1 => 0
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