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92a97015
by Simon Peyton Jones at 2026-04-05T00:58:57+01:00
Add Invariant (NoTypeShadowing) to Core
This commit addresses #26868, by adding
a new invariant (NoTypeShadowing) to Core.
See Note [No type-shadowing in Core] in GHC.Core
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8b5a5020
by Simon Peyton Jones at 2026-04-05T00:58:57+01:00
Major refactor of free-variable functions
For some time we have had two free-variable mechanims for types:
* The "FV" mechanism, embodied in GHC.Utils.FV, which worked OK, but
was fragile where eta-expansion was concerned.
* The TyCoFolder mechanism, using a one-shot EndoOS accumulator
I finally got tired of this and refactored the whole thing, thereby
addressing #27080. Now we have
* `GHC.Types.Var.FV`, which has a composable free-variable result type,
very much in the spirit of the old `FV`, but much more robust.
(It uses the "one shot trick".)
* GHC.Core.TyCo.FVs now has just one technology for free variables.
All this led to a lot of renaming.
There are couple of error-message changes. The change in T18451
makes an already-poor error message even more mysterious. But
it really needs a separate look.
We also now traverse the AST in a different order leading to a different
but still deterministic order for FVs and test output has been adjusted
accordingly.
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4bf040c6
by sheaf at 2026-04-05T14:56:29-04:00
Add utility pprTrace_ function
This function is useful for quick debugging, as it can be added to a
where clause to pretty-print debugging information:
fooBar x y
| cond = body1
| otherwise = body2
where
!_ = pprTrace_ "fooBar" $
vcat [ text "x:" <+> ppr x
, text "y:" <+> ppr y
, text "cond:" <+> ppr cond
]
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886ce194
by Cheng Shao at 2026-04-06T16:11:30+02:00
ghci: use ShortByteString for LookupSymbol/LookupSymbolInDLL/LookupClosure messages
This patch refactors ghci to use `ShortByteString` for
`LookupSymbol`/`LookupSymbolInDLL`/`LookupClosure` messages as the
first part of #27147.
Co-authored-by: Codex <codex@openai.com>
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35063998
by Cheng Shao at 2026-04-06T18:24:49+00:00
ghci: use ShortByteString for MkCostCentres message
This patch refactors ghci to use `ShortByteString` for `MkCostCentres`
messages as a first part of #27147. This also considerably lowers the
memory overhead of breakpoints when cost center profiling is enabled.
Co-authored-by: Codex <codex@openai.com>