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| author | Teo Camarasu <teofilcamarasu@gmail.com> | 2022-09-21 10:44:49 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2022-10-21 13:23:07 -0400 |
| commit | 09ec7de23ea826cb7ac25cb96a214808693de377 (patch) | |
| tree | a756383570a27f149a9563b5f07cb7c9f33e931e /libraries/template-haskell/Language/Haskell/TH | |
| parent | b8304648731f1430dba9037f31107d75b3da78b0 (diff) | |
| download | haskell-09ec7de23ea826cb7ac25cb96a214808693de377.tar.gz | |
template-haskell: Improve documentation of strictness annotation types
Before it was undocumentated that DecidedLazy can be returned by
reifyConStrictness for strict fields. This can happen when a field has
an unlifted type or its the single field of a newtype constructor.
Fixes #21380
Diffstat (limited to 'libraries/template-haskell/Language/Haskell/TH')
| -rw-r--r-- | libraries/template-haskell/Language/Haskell/TH/Syntax.hs | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/libraries/template-haskell/Language/Haskell/TH/Syntax.hs b/libraries/template-haskell/Language/Haskell/TH/Syntax.hs index 2fb37e742b..0c74758fa6 100644 --- a/libraries/template-haskell/Language/Haskell/TH/Syntax.hs +++ b/libraries/template-haskell/Language/Haskell/TH/Syntax.hs @@ -2617,24 +2617,36 @@ type Cxt = [Pred] -- ^ @(Eq a, Ord b)@ -- be tuples of other constraints. type Pred = Type +-- | 'SourceUnpackedness' corresponds to unpack annotations found in the source code. +-- +-- This may not agree with the annotations returned by 'reifyConStrictness'. +-- See 'reifyConStrictness' for more information. data SourceUnpackedness = NoSourceUnpackedness -- ^ @C a@ | SourceNoUnpack -- ^ @C { {\-\# NOUNPACK \#-\} } a@ | SourceUnpack -- ^ @C { {\-\# UNPACK \#-\} } a@ deriving (Show, Eq, Ord, Data, Generic) +-- | 'SourceStrictness' corresponds to strictness annotations found in the source code. +-- +-- This may not agree with the annotations returned by 'reifyConStrictness'. +-- See 'reifyConStrictness' for more information. data SourceStrictness = NoSourceStrictness -- ^ @C a@ | SourceLazy -- ^ @C {~}a@ | SourceStrict -- ^ @C {!}a@ deriving (Show, Eq, Ord, Data, Generic) -- | Unlike 'SourceStrictness' and 'SourceUnpackedness', 'DecidedStrictness' --- refers to the strictness that the compiler chooses for a data constructor --- field, which may be different from what is written in source code. See --- 'reifyConStrictness' for more information. -data DecidedStrictness = DecidedLazy - | DecidedStrict - | DecidedUnpack +-- refers to the strictness annotations that the compiler chooses for a data constructor +-- field, which may be different from what is written in source code. +-- +-- Note that non-unpacked strict fields are assigned 'DecidedLazy' when a bang would be inappropriate, +-- such as the field of a newtype constructor and fields that have an unlifted type. +-- +-- See 'reifyConStrictness' for more information. +data DecidedStrictness = DecidedLazy -- ^ Field inferred to not have a bang. + | DecidedStrict -- ^ Field inferred to have a bang. + | DecidedUnpack -- ^ Field inferred to be unpacked. deriving (Show, Eq, Ord, Data, Generic) -- | A single data constructor. |