From 40fa237e1daab7a76b9871bb6c50b953a1addf23 Mon Sep 17 00:00:00 2001
From: Krzysztof Gogolewski <krzysztof.gogolewski@tweag.io>
Date: Mon, 15 Jun 2020 19:58:10 +0200
Subject: Linear types (#15981)

This is the first step towards implementation of the linear types proposal
(https://github.com/ghc-proposals/ghc-proposals/pull/111).

It features

* A language extension -XLinearTypes
* Syntax for linear functions in the surface language
* Linearity checking in Core Lint, enabled with -dlinear-core-lint
* Core-to-core passes are mostly compatible with linearity
* Fields in a data type can be linear or unrestricted; linear fields
  have multiplicity-polymorphic constructors.
  If -XLinearTypes is disabled, the GADT syntax defaults to linear fields

The following items are not yet supported:

* a # m -> b syntax (only prefix FUN is supported for now)
* Full multiplicity inference (multiplicities are really only checked)
* Decent linearity error messages
* Linear let, where, and case expressions in the surface language
  (each of these currently introduce the unrestricted variant)
* Multiplicity-parametric fields
* Syntax for annotating lambda-bound or let-bound with a multiplicity
* Syntax for non-linear/multiple-field-multiplicity records
* Linear projections for records with a single linear field
* Linear pattern synonyms
* Multiplicity coercions (test LinearPolyType)

A high-level description can be found at
https://ghc.haskell.org/trac/ghc/wiki/LinearTypes/Implementation
Following the link above you will find a description of the changes made to Core.
This commit has been authored by

* Richard Eisenberg
* Krzysztof Gogolewski
* Matthew Pickering
* Arnaud Spiwack

With contributions from:

* Mark Barbone
* Alexander Vershilov

Updates haddock submodule.
---
 compiler/GHC/Tc/Deriv/Functor.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'compiler/GHC/Tc/Deriv/Functor.hs')

diff --git a/compiler/GHC/Tc/Deriv/Functor.hs b/compiler/GHC/Tc/Deriv/Functor.hs
index 6a13cfaccd..a1af9166fe 100644
--- a/compiler/GHC/Tc/Deriv/Functor.hs
+++ b/compiler/GHC/Tc/Deriv/Functor.hs
@@ -40,6 +40,7 @@ import GHC.Tc.Utils.TcType
 import GHC.Core.TyCon
 import GHC.Core.TyCo.Rep
 import GHC.Core.Type
+import GHC.Core.Multiplicity
 import GHC.Utils.Misc
 import GHC.Types.Var
 import GHC.Types.Var.Set
@@ -557,7 +558,7 @@ deepSubtypesContaining tv
 foldDataConArgs :: FFoldType a -> DataCon -> [a]
 -- Fold over the arguments of the datacon
 foldDataConArgs ft con
-  = map foldArg (dataConOrigArgTys con)
+  = map foldArg (map scaledThing $ dataConOrigArgTys con)
   where
     foldArg
       = case getTyVar_maybe (last (tyConAppArgs (dataConOrigResTy con))) of
-- 
cgit v1.2.1