Foreign.Marshal.Error

Routines for testing return values and raising a userError exception in case of values indicating an error state.

Documentation

throwIf

Arguments

∷ (a → Bool)

error condition on the result of the IO action

→ (a → String)

computes an error message from erroneous results of the IO action

→ IO a

the IO action to be executed

→ IO a

Execute an IO action, throwing a userError if the predicate yields True when applied to the result returned by the IO action. If no exception is raised, return the result of the computation.

throwIf_ ∷ (a → Bool) → (a → String) → IO a → IO ()

Like throwIf, but discarding the result

throwIfNeg ∷ (Ord a, Num a) ⇒ (a → String) → IO a → IO a

Guards against negative result values

throwIfNeg_ ∷ (Ord a, Num a) ⇒ (a → String) → IO a → IO ()

Like throwIfNeg, but discarding the result

throwIfNull ∷ String → IO (Ptr a) → IO (Ptr a)

Guards against null pointers

void ∷ IO a → IO ()

Deprecated: use void instead

Discard the return value of an IO action