úÎ!,„  IUsed to indicate the frequency of a computation in a single permutation, ' changing the result type accordingly. A chain of effectful f -computations with final result a . Individual  computations (lifted into Effects( using one of the frequency combinators D below) have their own result types, which fit together in standard  8 fashion. Although these result types are existentially M quantified, the computations can still be moved around within the list (see   and 5 in the source code for examples). This allows their  permutations to be computed. .Compute the length of a list of computations. ,Run a computation with a certain frequency. JSplits a frequency such that the first effect in the result always occurs  exactly . 6Run the computation exactly once in each permutation. CRun the computation exactly zero or one times in each permutation. @Run the computation at least so many times in each permutation. ERun the computation between so and so many times (inclusive) in each  permutation. ?Run the computation exactly so many times in each permutation. <Run the computation zero or more times in each permutation. ;Run the computation one or more times in each permutation. 8Run the effects in order, respecting their frequencies. Build a tree (using + for branching) of all permutations of the L computations. The tree shape allows permutations to share common prefixes. E This allows clever computations to quickly prune away uninteresting  branches of permutations. IGive each effect a chance to be the first effect in the chain, producing  n new chains where n is the " of the input chain. In each case M the relative order of the effects is preserved with exception of the effect  that was moved to the front. 9Swaps the first two elements of the list, if they exist. 1 represents the empty list of computations while  acts like  .  Map over the final result type.          !"#$%PermuteEffects-0.1.1Control.Applicative.PermuteEffectsonceoptatLeastbetweenexactlymanysomepermsFreqBetweenAtLeastOptOncebaseControl.Applicative Applicativeswapfirsts:-NillengthrunFreqfreqMatchesEpsiloneffectsMatchEpsilonsplitlift runEffects<|>$fApplicativeEffectspure<*>GHC.Base++$fFunctorEffects