errors

Simplified error-handling

Version on this page:2.3.0@rev:1
LTS Haskell 23.27:2.3.0@rev:5
Stackage Nightly 2025-07-06:2.3.0@rev:5
Latest on Hackage:2.3.0@rev:5

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BSD-3-Clause licensed by Gabriel Gonzalez
Maintained by [email protected]
This version can be pinned in stack with:errors-2.3.0@sha256:377ffba00149eba85e269df3392eea461cde7cd8f7325e17dd2270cbed01c623,1429

Module documentation for 2.3.0

The one-stop shop for all your error-handling needs! Just import Control.Error.

This library encourages an error-handling style that directly uses the type system, rather than out-of-band exceptions.

Changes

2.3.0

2.2.5

  • Increase upper bound on exceptions

2.2.4

  • Increase upper bound on exceptions

2.2.3

  • Increase upper bound on transformers-compat

2.2.2

  • Support GHC 8.4 through compatibility with Semigroup/Monoid proposal

2.2.1

  • Add precedence and fixity for (?:)

2.2.0

  • BREAKING CHANGE: Use Text instead of String
  • Add handleExceptT

2.1.3

  • Support older versions of ghc

2.1.2

  • Increase upper bound on transformers dependency

2.1.1

  • Increase upper bound on transformers-compat

2.1.0

  • Change syncio to use unexceptionalio to prove that all synchronous exceptions were caught and handled

2.0.0

  • Switch from EitherT to ExceptT

1.4.7

  • Increase upper bound on transformers from 0.4 to 0.5

1.4.6

  • Add bool
  • Add (?:)
  • Add isJustT
  • Add isNothingT
  • Add isLeftT
  • Add isRightT

1.4.5

  • Increase upper bound on either from 4.1 to 5

1.4.4

  • Add failWith
  • Add failWithM

1.4.3

  • Add AllE
  • Add AnyE
  • Increase upper bound on either from 3.5 to 4.1

1.4.2

  • Add (??)
  • Add (!?)
  • Add syncIO

1.4.1

  • Re-export EitherT
  • Re-export MaybeT

1.4.0

  • Add maybeT
  • Add just
  • Add nothing
  • Add upper bound to either
  • Add upper bound to safe
  • Add upper bound to transformers

1.3.1

  • Increase lower bound on transformers from 0.2 to 0.3.0.0

1.3.0

  • Add assertMay
  • Add rightMay
  • Add justErr
  • Add tryJust
  • Add tryRight
  • Add MonadPlus functions to Control.Error.Safe
  • Add isLeft
  • Add isRight
  • Add fmapR
  • Add fmapRT
  • Add err
  • Add errLn
  • Add flipE
  • Add flipET
  • Rename tryIO to scriptIO
  • Remove tryMaybe
  • Remove tryEither
  • Rename liftMaybe to hoistMaybe
  • Rename liftEither to hoistEither

1.2.1

  • Add lower bound to either

1.2.0

  • Remove right
  • Remove left

1.1.1

  • Cosmetic changes

1.1.0

  • Add left

1.0.0

  • Initial release