How to load & parse an HI (interface) file?

[Sebastian Graf]

Hey,

there's this relatively recent thread on finding instances of a type class:

https://mail.haskell.org/pipermail/ghc-devs/2017-May/014217.html

I'm sorry, but I couldn't find a better archive for ghc-devs.

Enjoy
Sebastian

On Sun, Dec 3, 2017 at 3:43 AM, Brandon Allbery <allbery.b at gmail.com> wrote:

> The problem with the API is it's complex and can break between ghc
> versions.
> But --show-iface is even more fragile and prone to break between ghc
> versions.
> The history of the plugins package constitutes a record of both kinds of
> pain.
>
> On Sat, Dec 2, 2017 at 9:11 PM, Saurabh Nanda <saurabhnanda at gmail.com>
> wrote:
>
>> > I would be cautious about using the ghc-api hi file interfaces; hi
>> files turn out to interact with a
>> > lot of low-level parts in complex ways (even to the extent that they're
>> a large part of why ghc
>> > can't parallelize builds itself and attempts to change that have mostly
>> failed).
>>
>> Are you cautioning against using the GHC API (as opposed to the
>> --show-iface command line interface)
>> or using HI files themselves?
>>
>> -- Saurabh.
>>
>>
>> On Sun, Dec 3, 2017 at 2:04 AM, Brandon Allbery <allbery.b at gmail.com>
>> wrote:
>>
>>> I would be cautious about using the ghc-api hi file interfaces; hi files
>>> turn out to interact with a lot of low-level parts in complex ways (even to
>>> the extent that they're a large part of why ghc can't parallelize builds
>>> itself and attempts to change that have mostly failed).
>>>
>>> But if you must do this, you *really* want to have
>>> https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler ready to hand
>>> --- and go through it first so you have some idea of how it works; much of
>>> it is links to the lower level details (often straight into the source).
>>>
>>> On Sat, Dec 2, 2017 at 10:59 AM, Saurabh Nanda <saurabhnanda at gmail.com>
>>> wrote:
>>>
>>>> (GHC newbie alert -- is this the right mailing list for these kind of
>>>> questions?)
>>>>
>>>> I"m writing some code to figure out all the instances of particular
>>>> type-classes and after exploring a lot of options (hlint, haskell-src-exts,
>>>> annotations, doctests, etc), I realized that the compiler had already
>>>> figured it out and written it to disk for me!
>>>>
>>>> More digging led me to https://www.stackage.org/haddo
>>>> ck/lts-9.0/ghc-8.0.2/LoadIface.html#v:loadSrcInterface after which I
>>>> got stuck. How does one call this function? Specifically:
>>>>
>>>> * What is SDoc and how to construct a reasonable value for this
>>>> argument?
>>>> * IsBootInterface would mostly be False, right?
>>>> * What does `Maybe FastString` represent and how does one construct it?
>>>> * Finally how does one evaluate the resulting monadic action to get
>>>> access to the underlying `ModIface`?
>>>>
>>>> -- Saurabh.
>>>>
>>>>
>>>> _______________________________________________
>>>> ghc-devs mailing list
>>>> ghc-devs at haskell.org
>>>> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
>>>>
>>>>
>>>
>>>
>>> --
>>> brandon s allbery kf8nh                               sine nomine
>>> associates
>>> allbery.b at gmail.com
>>> ballbery at sinenomine.net
>>> unix, openafs, kerberos, infrastructure, xmonad
>>> http://sinenomine.net
>>>
>>
>>
>>
>> --
>> http://www.saurabhnanda.com
>>
>
>
>
> --
> brandon s allbery kf8nh                               sine nomine
> associates
> allbery.b at gmail.com
> ballbery at sinenomine.net
> unix, openafs, kerberos, infrastructure, xmonad
> http://sinenomine.net
>
> _______________________________________________
> ghc-devs mailing list
> ghc-devs at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
>
>
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