Bluefin.Exception

Handle

data Exception e (ex :: Effects)

Handle to an exception of type e

Instances

e :> es => MonadFail (EffReader (Exception String e) es)

Defined in Bluefin.Internal

Methods

fail :: String -> EffReader (Exception String e) es a

Handlers

try

Arguments

:: forall e (es :: Effects) a. (forall (ex :: Effects). Exception e ex -> Eff (ex :& es) a)

-> Eff es (Either e a)

Left if the exception was thrown, Right otherwise

>>> runPureEff $ try $ \e -> do
      throw e 42
      pure "No exception thrown"
Left 42

handle

Arguments

:: forall e (es :: Effects) a. (e -> Eff es a)

If the exception is thrown, apply this handler

-> (forall (ex :: Effects). Exception e ex -> Eff (ex :& es) a)

-> Eff es a

handle, but with the argument order swapped

>>> runPureEff $ handle (pure . show) $ \e -> do
      throw e 42
      pure "No exception thrown"
"42"

catch

Arguments

:: forall e (es :: Effects) a. (forall (ex :: Effects). Exception e ex -> Eff (ex :& es) a)

-> (e -> Eff es a)

If the exception is thrown, apply this handler

-> Eff es a

Effectful operations

throw

Arguments

:: forall (ex :: Effects) (es :: Effects) e a. ex :> es

=> Exception e ex

-> e

Value to throw

-> Eff es a

>>> runPureEff $ try $ \e -> do
      throw e 42
      pure "No exception thrown"
Left 42

>>> runPureEff $ try $ \e -> do
      pure "No exception thrown"
Right "No exception thrown"