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

Saurabh Nanda saurabhnanda at gmail.com
Sun Dec 3 02:11:43 UTC 2017


> 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.
>>
>>
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>> ghc-devs at haskell.org
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>>
>>
>
>
> --
> 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
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