[GHC] #15646: ghci takes super long time to find the type of large fractional number
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Fri Dec 28 11:13:48 UTC 2018
#15646: ghci takes super long time to find the type of large fractional number
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Reporter: Johannkokos | Owner:
| JulianLeviston
Type: bug | Status: new
Priority: normal | Milestone: 8.6.1
Component: GHCi | Version: 8.4.3
Resolution: | Keywords: newcomer
Operating System: Unknown/Multiple | Architecture:
Type of failure: Compile-time | Unknown/Multiple
performance bug | Test Case:
Blocked By: | Blocking:
Related Tickets: #5692 | Differential Rev(s):
Wiki Page: |
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Comment (by JulianLeviston):
The current problems are:
##Problem 1##
As we need to store an application of `mkRational` upon desugaring, we
need to have it exist in some library. Unfortunately, for Stage 1
compilation, the library functions we have access to seem to be only those
that exist in the *GHC that is compiling* rather than the *GHC that is
being compiled*.
This means the reference to `mkRationalName` that I've added to
`PrelNames.hs` doesn't work, because we can't refer to any module that has
the `mkRational` function in it; none exist. Of course, there is every
chance we're not aware of a way to inject the bootstrapped code in — how
does one refer to new library functions?
Note: initially, and in the current fork as I've written it, I refer to it
via `gHC_REAL` but that obviously doesn't work.
##Problem 2##
Typechecking is still slow (less slow, granted, but only a little). I
think this makes sense, as I haven't actually adjusted any typechecker
code yet. I've been looking into `TcExpr.hs` which has the `tcExpr`
function, but I need to figure through that code.
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15646#comment:67>
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