HORIZON HASKELLDocslts/ghc-10.0.xfc4e5982026-10-11Search names, modules, packages, or :: a typeCtrl K

GHC 10.0.0.20260917 · lts/ghc-10.0.x · fc4e598 · 2026-10-11

Modulecabal-install-solver-3.18.1.0Haskell2010

Distribution.Solver.Modular.ConflictSet

Conflict sets

Intended for double import

import Distribution.Solver.Modular.ConflictSet (ConflictSet)
import qualified Distribution.Solver.Modular.ConflictSet as CS
  • 4 types
  • 17 values
newtypenewtype ConflictSet
#

The set of variables involved in a solver conflict, each paired with details about the conflict.

Instances2Eq, Show
  • Eq ConflictSetDefined in cabal-install-solver-3.18.1.0 · Distribution.Solver.Modular.ConflictSet
  • Show ConflictSetDefined in cabal-install-solver-3.18.1.0 · Distribution.Solver.Modular.ConflictSet
datadata Conflict
#

More detailed information about how a conflict set variable caused a conflict. This information can be used to determine whether a second value for that variable would lead to the same conflict.

TODO: Handle dependencies under flags or stanzas.

Constructors

  • GoalConflict QPN

    The conflict set variable represents a package which depends on the specified problematic package. For example, the conflict set entry '(P x, GoalConflict y)' means that package x introduced package y, and y led to a conflict.

  • VersionConstraintConflict QPN Ver

    The conflict set variable represents a package with a constraint that excluded the specified package and version. For example, the conflict set entry '(P x, VersionConstraintConflict y (mkVersion [2, 0]))' means that package x's constraint on y excluded y-2.0.

  • VersionConflict QPN OrderedVersionRange

    The conflict set variable represents a package that was excluded by a constraint from the specified package. For example, the conflict set entry '(P x, VersionConflict y (orLaterVersion (mkVersion [2, 0])))' means that package y's constraint 'x >= 2.0' excluded some version of x.

  • OtherConflict

    Any other conflict.

Instances3Eq, Ord, Show
  • Eq ConflictDefined in cabal-install-solver-3.18.1.0 · Distribution.Solver.Modular.ConflictSet
  • Ord ConflictDefined in cabal-install-solver-3.18.1.0 · Distribution.Solver.Modular.ConflictSet
  • Show ConflictDefined in cabal-install-solver-3.18.1.0 · Distribution.Solver.Modular.ConflictSet
valuefilter :: (a -> Bool) -> [a] -> [a]
#

\mathcal{O}(n). filter, applied to a predicate and a list, returns the list of those elements that satisfy the predicate; i.e.,

filter p xs = [ x | x <- xs, p x]
Examples
Example1 expression
filter odd [1, 2, 3][1,3]
Example1 expression
filter (\l -> length l > 3) ["Hello", ", ", "World", "!"]["Hello","World"]
Example1 expression
filter (/= 3) [1, 2, 3, 4, 3, 2, 1][1,2,4,2,1]