5aed8b3ef5
Functions must be annotated as `stateful` in order to - Update the contract state (using `put`) - Call `Chain.spend` or other primitive functions that cost tokens - Call an Oracle or AENS function that requires a signature - Make a remote call with a non-zero value - Construct a lambda calling a stateful function It does not need to be stateful to - Read the contract state - Call another contract with value=0, even when the remote function is stateful
55 lines
1.8 KiB
Plaintext
55 lines
1.8 KiB
Plaintext
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contract Remote =
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stateful function remote_spend : (address, int) => ()
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function remote_pure : int => int
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contract Stateful =
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private function pure(x) = x + 1
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private stateful function local_spend(a) =
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Chain.spend(a, 1000)
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// Non-stateful functions cannot mention stateful functions
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function fail1(a : address) = Chain.spend(a, 1000)
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function fail2(a : address) = local_spend(a)
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function fail3(a : address) =
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let foo = Chain.spend
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foo(a, 1000)
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// Private functions must also be annotated
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private function fail4(a) = Chain.spend(a, 1000)
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// If annotated, stateful functions are allowed
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stateful function ok1(a : address) = Chain.spend(a, 1000)
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// And pure functions are always allowed
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stateful function ok2(a : address) = pure(5)
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stateful function ok3(a : address) =
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let foo = pure
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foo(5)
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// No error here (fail4 is annotated as not stateful)
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function ok4(a : address) = fail4(a)
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// Lamdbas are checked at the construction site
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private function fail5() : address => () = (a) => Chain.spend(a, 1000)
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// .. so you can pass a stateful lambda to a non-stateful higher-order
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// function:
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private function apply(f : 'a => 'b, x) = f(x)
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stateful function ok5(a : address) =
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apply((val) => Chain.spend(a, val), 1000)
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// It doesn't matter if remote calls are stateful or not
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function ok6(r : Remote) = r.remote_spend(Contract.address, 1000)
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function ok7(r : Remote) = r.remote_pure(5)
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// But you can't send any tokens if not stateful
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function fail6(r : Remote) = r.remote_spend(value = 1000, Contract.address, 1000)
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function fail7(r : Remote) = r.remote_pure(value = 1000, 5)
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function fail8(r : Remote) =
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let foo = r.remote_pure
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foo(value = 1000, 5)
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function ok8(r : Remote) = r.remote_spend(Contract.address, 1000, value = 0)
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