Update sophia.md

docs/sophia.md

@@ -8,7 +8,6 @@
 - [Language Features](#language-features)
     - [Contracts](#contracts)
         - [Calling other contracts](#calling-other-contracts)
-        - [Protected contract calls](#protected-contract-calls)
         - [Mutable state](#mutable-state)
             - [Stateful functions](#stateful-functions)
         - [Payable](#payable)
@@ -143,36 +142,6 @@ without calling it you can write
     Chain.spend(v.address, amount)
 ```
 
-#### Protected contract calls
-
-If a contract call fails for any reason (for instance, the remote contract
-crashes or runs out of gas, or the entrypoint doesn't exist or has the wrong
-type) the parent call also fails. To make it possible to recover from failures,
-contract calls takes a named argument `protected : bool` (default `false`).
-
-The protected argument must be a literal boolean, and when set to `true`
-changes the type of the contract call, wrapping the result in an `option` type.
-If the call fails the result is `None`, otherwise it's `Some(r)` where `r` is
-the return value of the call.
-
-```sophia
-contract VotingType =
-  entrypoint : vote : string => unit
-
-contract Voter =
-  entrypoint tryVote(v : VotingType, alt : string) =
-    switch(v.vote(alt, protected = true) : option(unit))
-      None    => "Voting failed"
-      Some(_) => "Voting successful"
-```
-
-Any gas that was consumed by the contract call before the failure stays
-consumed, which means that in order to protect against the remote contract
-running out of gas it is necessary to set a gas limit using the `gas` argument.
-However, note that errors that would normally consume all the gas in the
-transaction still only uses up the gas spent running the contract.
-
-
 ### Mutable state
 
 Sophia does not have arbitrary mutable state, but only a limited form of