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Eliminate some ambiguity for IsString [a]

    • Closed Issue created by dolio @trac-dolio

    The libraries list resolved to make a modification to the String instance for IsString to resolve certain ambiguous cases. One example is:

    "hello" ++ " world"

    This case can be resolved by making the instance:

    instance (a ~ Char) => IsString [a] where ...

    rather than:

    instance IsString [Char] where ...

    as the former matches only based on the head being [a], and subsequently determines a ~ Char, rather than only matching when other factors cause the head to be fully resolved to [Char].

    Trac metadata
    Trac field Value
    Version 7.10.2
    Type Task
    TypeOfFailure OtherFailure
    Priority normal
    Resolution Unresolved
    Component Core Libraries
    Test case
    Differential revisions
    BlockedBy
    Related
    Blocking
    CC
    Operating system
    Architecture
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