name:               ChasingBottoms
version:            1.3.1.15
x-revision: 1
license:            MIT
license-file:       LICENCE
copyright:          Copyright (c) Nils Anders Danielsson 2004-2022, 2024.
author:             Nils Anders Danielsson
maintainer:         http://www.cse.chalmers.se/~nad/
synopsis:           For testing partial and infinite values.
description:
  Do you ever feel the need to test code involving bottoms (e.g. calls to
  the @error@ function), or code involving infinite values? Then this
  library could be useful for you.
  .
  It is usually easy to get a grip on bottoms by showing a value and
  waiting to see how much gets printed before the first exception is
  encountered. However, that quickly gets tiresome and is hard to automate
  using e.g. QuickCheck
  (<http://www.cse.chalmers.se/~rjmh/QuickCheck/>). With this library you
  can do the tests as simply as the following examples show.
  .
  Testing explicitly for bottoms:
  .
  > > isBottom (head [])
  > True
  .
  > > isBottom bottom
  > True
  .
  > > isBottom (\_ -> bottom)
  > False
  .
  > > isBottom (bottom, bottom)
  > False
  .
  Comparing finite, partial values:
  .
  > > ((bottom, 3) :: (Bool, Int)) ==! (bottom, 2+5-4)
  > True
  .
  > > ((bottom, bottom) :: (Bool, Int)) <! (bottom, 8)
  > True
  .
  Showing partial and infinite values (@\\\/!@ is join and @\/\\!@ is meet):
  .
  > > approxShow 4 $ (True, bottom) \/! (bottom, 'b')
  > "Just (True, 'b')"
  .
  > > approxShow 4 $ (True, bottom) /\! (bottom, 'b')
  > "(_|_, _|_)"
  .
  > > approxShow 4 $ ([1..] :: [Int])
  > "[1, 2, 3, _"
  .
  > > approxShow 4 $ (cycle [bottom] :: [Bool])
  > "[_|_, _|_, _|_, _"
  .
  Approximately comparing infinite, partial values:
  .
  > > approx 100 [2,4..] ==! approx 100 (filter even [1..] :: [Int])
  > True
  .
  > > approx 100 [2,4..] /=! approx 100 (filter even [bottom..] :: [Int])
  > True
  .
  The code above relies on the fact that @bottom@, just as @error
  \"...\"@, @undefined@ and pattern match failures, yield
  exceptions. Sometimes we are dealing with properly non-terminating
  computations, such as the following example, and then it can be nice to
  be able to apply a time-out:
  .
  > > timeOut' 1 (reverse [1..5])
  > Value [5,4,3,2,1]
  .
  > > timeOut' 1 (reverse [1..])
  > NonTermination
  .
  The time-out functionality can be used to treat \"slow\" computations as
  bottoms:
  .
  @
  \> let tweak = Tweak &#x7b; approxDepth = Just 5, timeOutLimit = Just 2 &#x7d;
  \> semanticEq tweak (reverse [1..], [1..]) (bottom :: [Int], [1..] :: [Int])
  True
  @
  .
  @
  \> let tweak = noTweak &#x7b; timeOutLimit = Just 2 &#x7d;
  \> semanticJoin tweak (reverse [1..], True) ([] :: [Int], bottom)
  Just ([],True)
  @
  .
  This can of course be dangerous:
  .
  @
  \> let tweak = noTweak &#x7b; timeOutLimit = Just 0 &#x7d;
  \> semanticEq tweak (reverse [1..100000000]) (bottom :: [Integer])
  True
  @
  .
  Timeouts can also be applied to @IO@ computations:
  .
  > > let primes () = unfoldr (\(x:xs) -> Just (x, filter ((/= 0) . (`mod` x)) xs)) [2..]
  > > timeOutMicro 100 (print $ primes ())
  > [2,NonTermination
  > > timeOutMicro 10000 (print $ take 10 $ primes ())
  > [2,3,5,7,11,13,17,19,23,29]
  > Value ()
  .
  For the underlying theory and a larger example involving use of
  QuickCheck, see the article \"Chasing Bottoms, A Case Study in Program
  Verification in the Presence of Partial and Infinite Values\"
  (<http://www.cse.chalmers.se/~nad/publications/danielsson-jansson-mpc2004.html>).
  .
  The code has been tested using GHC. Most parts can probably be
  ported to other Haskell compilers, but this would require some work.
  The @TimeOut@ functions require preemptive scheduling, and most of
  the rest requires @Data.Generics@; @isBottom@ only requires
  exceptions, though.
category:           Testing
tested-with:        GHC == 8.0.2,
                    GHC == 8.2.2,
                    GHC == 8.4.4,
                    GHC == 8.6.5,
                    GHC == 8.8.4,
                    GHC == 8.10.5,
                    GHC == 9.0.2,
                    GHC == 9.2.8,
                    GHC == 9.4.8,
                    GHC == 9.6.6,
                    GHC == 9.8.2,
                    GHC == 9.10.1
cabal-version:      >= 1.10
build-type:         Simple

source-repository head
  type:     darcs
  location: http://www.cse.chalmers.se/~nad/repos/ChasingBottoms/

library
    exposed-modules:
        Test.ChasingBottoms,
        Test.ChasingBottoms.Approx,
        Test.ChasingBottoms.ApproxShow,
        Test.ChasingBottoms.ContinuousFunctions,
        Test.ChasingBottoms.IsBottom,
        Test.ChasingBottoms.Nat,
        Test.ChasingBottoms.SemanticOrd,
        Test.ChasingBottoms.TimeOut

    other-modules: Test.ChasingBottoms.IsType

    default-language: Haskell2010

    if impl(ghc >= 7.4.1)
      ghc-options: -fpedantic-bottoms

    build-depends: QuickCheck >= 2.10 && < 2.16,
                   mtl >= 2 && < 2.4,
                   base >= 4.2 && < 4.22,
                   containers >= 0.5 && < 0.8,
                   random >= 1.0 && < 1.3,
                   syb >= 0.1.0.2 && < 0.8

test-suite ChasingBottomsTestSuite
    type:          exitcode-stdio-1.0

    main-is:       Test/ChasingBottoms/Tests.hs

    other-modules: Test.ChasingBottoms.Approx,
                   Test.ChasingBottoms.Approx.Tests,
                   Test.ChasingBottoms.ApproxShow,
                   Test.ChasingBottoms.ApproxShow.Tests,
                   Test.ChasingBottoms.ContinuousFunctions,
                   Test.ChasingBottoms.ContinuousFunctions.Tests,
                   Test.ChasingBottoms.IsBottom,
                   Test.ChasingBottoms.IsBottom.Tests,
                   Test.ChasingBottoms.IsType,
                   Test.ChasingBottoms.IsType.Tests,
                   Test.ChasingBottoms.Nat,
                   Test.ChasingBottoms.Nat.Tests,
                   Test.ChasingBottoms.SemanticOrd,
                   Test.ChasingBottoms.SemanticOrd.Tests,
                   Test.ChasingBottoms.TestUtilities,
                   Test.ChasingBottoms.TestUtilities.Generators,
                   Test.ChasingBottoms.TimeOut
                   Test.ChasingBottoms.TimeOut.Tests

    default-language: Haskell2010

    if impl(ghc >= 7.4.1)
      ghc-options: -fpedantic-bottoms

    build-depends: QuickCheck >= 2.10 && < 2.16,
                   mtl >= 2 && < 2.4,
                   base >= 4.2 && < 4.21,
                   containers >= 0.5 && < 0.8,
                   random >= 1.0 && < 1.3,
                   syb >= 0.1.0.2 && < 0.8,
                   array >= 0.3 && < 0.6