# Ticket #15 (new defect)

Opened 5 years ago

## Events don't hold monad laws

Reported by: | camio | Owned by: | |
---|---|---|---|

Priority: | major | Milestone: | |

Version: | Keywords: | ||

Cc: |

### Description

m :: EventG X String m = listToEvent [future 1 "m0"] f,g :: String -> EventG X String f = const $ listToEvent [ future 0 "f0" , future 0 "f1" ] g = const $ listToEvent [ future 0 "g0" , future 1 "g1" ] a = (m >>= f) >>= g -- ((1,m0) >>= f) >>= g -- [(1,f0), (1,f1)] >>= g -- [(1,g0), (1,g1), (1,g0), (1,g1)] b = m >>= (\x -> f x >>= g) -- m >>= (\x -> f x >>= g) -- m >>= ([(0,f0), (0,f1)] >>= g) -- m >>= [(0,g0), (0,g0), (1,g1), (1,g1)] -- [(1,g0), (1,g0), (1,g1), (1,g1)]

Beneath a and b is a calculation of the result in the semantic domain. This serves as a counter example of the assertion that joinE as defined in section 2.2.3 of the paper forms a monad with the rest of the things (list equality, fmap, etc.).

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