Module Tezos_raw_protocol_012_Psithaca.Gas_monad

type ('a, 'trace) t

This monad combines:

  • a state monad where the state is the context
  • two levels of error monad to distinguish gas exhaustion from other errors

It is useful for backtracking on type checking errors without backtracking the consumed gas.

type ('a, 'trace) gas_monad = ('a, 'trace) t

Alias of ('a, 'trace) t to avoid confusion when the module is open

val return : 'a -> ('a, 'trace) t

monadic return operator of the gas monad

val (>>$) : ('a, 'trace) t -> ('a -> ('b, 'trace) t) -> ('b, 'trace) t

Binding operator for the gas monad

val (>|$) : ('a, 'trace) t -> ('a -> 'b) -> ('b, 'trace) t

Mapping operator for the gas monad, m >|$ f is equivalent to m >>$ fun x -> return (f x)

val (>?$) : ('a, 'trace) t -> ('a -> ('b, 'trace) Tezos_protocol_environment_012_Psithaca.Pervasives.result) -> ('b, 'trace) t

Variant of ( >>$ ) to bind uncarbonated functions

val (>??$) : ('a, 'trace) t -> (('a, 'trace) Tezos_protocol_environment_012_Psithaca.Pervasives.result -> ('b, 'trace) t) -> ('b, 'trace) t

Another variant of ( >>$ ) that lets recover from inner errors

val of_result : ('a, 'trace) Tezos_protocol_environment_012_Psithaca.Pervasives.result -> ('a, 'trace) t

gas-free embedding of tzresult values. of_result x is equivalent to return () >?$ fun () -> x

val consume_gas : Alpha_context.Gas.cost -> (unit, 'trace) t

A wrapper around Gas.consume. If that fails, the whole computation within the Gas_monad returns an error. See the Alpha_context.Gas module for details.

Escaping the gas monad

re-export of Error_monad.record_trace_eval. This function has no effect in the case of a gas-exhaustion error.