Re: Abstract FilePath Proposal

-1 on this proposal in all its variations right now. There seems to be no strong consensus on the positive nature of any of the proposed changes at this point, and folks seem to disagree on the scope and content of the changes. We should leave well enough alone until someone has a proposal most of us can agree is awesome. On Sun, Jun 28, 2015 at 10:05 AM wrote:

One other point, while still maintaining +0 on the proposal itself:

This proposal is likely to break lots and lots of code a la the FTP, and we all remember the unpleasant surprise that the community had with that one.

If libraries@ agrees this is a worthwhile change, I think we need to let the community vote on it and its deprecation cycle.

Tom

El Jun 27, 2015, a las 3:36, Herbert Valerio Riedel escribió:

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On 2015-06-26 at 18:22:16 +0200, Henning Thielemann wrote: [...]

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type FilePath = String

into an abstract/opaque data type instead.

Has someone else tried the pathtype package? http://hackage.haskell.org/package/pathtype

Hm, your last point "Decisions assumed by this Proposal" seems to mean, that you want to leave out more specialised types from this proposal. That is, dir/file distinction might be defined on top of the new FilePath type.

Yes, because the proposal is meant to only make the smallest incremental change needed (i.e. change FilePath datatype, provide conversion functions) to to achieve the primary goals (reduce space/time overhead & make it a distinct type from String) in a way suitable for a future Haskell Report, while trying to stay close enough that you can still write code that works with both the H2010 and a AFPP definition of `FilePath`

Trying to redesign the FilePath type to also include dir/file distinction seemed too daunting, as there's quite some additional design-space area to explore (do drive-letters deserve a separate type? do we use DataKinds? What invariants can/shall be represented at the type-level? what errors are caught at the type-level, which are caught at runtime? etc...), parts of which may require type-system extensions, while just having a KISS-style opaque FilePath evades this.

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