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authorJoachim Breitner <mail@joachim-breitner.de>2014-01-30 16:28:00 +0000
committerJoachim Breitner <mail@joachim-breitner.de>2014-01-30 16:28:00 +0000
commit1dd38a54bb29387d9e9c549dbb020bc9ed4ecb91 (patch)
tree23cf422284edb28800253234ffac90935621e4af /compiler/prelude/primops.txt.pp
parent044f23388c0c316fbc470c93860797a30b3130bd (diff)
downloadhaskell-1dd38a54bb29387d9e9c549dbb020bc9ed4ecb91.tar.gz
Remove Coercible documentation from compiler/prelude/primops.txt.pp
We want it to show up in GHC.Exts, so we need to put the documentation in GHC.Types, where the datatype Coercible is defined.
Diffstat (limited to 'compiler/prelude/primops.txt.pp')
-rw-r--r--compiler/prelude/primops.txt.pp41
1 files changed, 0 insertions, 41 deletions
diff --git a/compiler/prelude/primops.txt.pp b/compiler/prelude/primops.txt.pp
index 36eec67b7d..d2978dc730 100644
--- a/compiler/prelude/primops.txt.pp
+++ b/compiler/prelude/primops.txt.pp
@@ -2365,47 +2365,6 @@ pseudoop "coerce"
}
primclass Coercible a b
- { This two-parameter class has instances for types {\tt a} and {\tt b} if
- the compiler can infer that they have the same representation. This class
- does not have regular instances; instead they are created on-the-fly during
- type-checking. Trying to manually declare an instance of {\tt Coercible}
- is an error.
-
- Nevertheless one can pretend that the following three kinds of instances
- exist. First, as a trivial base-case:
-
- {\tt instance a a}
-
- Furthermore, for every type constructor there is
- an instance that allows to coerce under the type constructor. For
- example, let {\tt D} be a prototypical type constructor ({\tt data} or {\tt
- newtype}) with three type arguments, which have roles Nominal,
- Representational resp. Phantom. Then there is an instance of the form
-
- {\tt instance Coercible b b' => Coercible (D a b c) (D a b' c')}
-
- Note that the nominal type arguments are equal, the representational type
- arguments can differ, but need to have a {\tt Coercible} instance
- themself, and the phantom type arguments can be changed arbitrarily.
-
- In SafeHaskell code, this instance is only usable if the constructors of
- every type constructor used in the definition of {\tt D} (including
- those of {\tt D} itself) are in scope.
-
- The third kind of instance exists for every {\tt newtype NT = MkNT T} and
- comes in two variants, namely
-
- {\tt instance Coercible a T => Coercible a NT}
-
- {\tt instance Coercible T b => Coercible NT b}
-
- This instance is only usable if the constructor {\tt MkNT} is in scope.
-
- If, as a library author of a type constructor like {\tt Set a}, you
- want to prevent a user of your module to write
- {\tt coerce :: Set T -> Set NT},
- you need to set the role of {\tt Set}'s type parameter to Nominal.
- }
------------------------------------------------------------------------
section "SIMD Vectors"