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| author | Oleg Grenrus <oleg.grenrus@iki.fi> | 2023-03-27 20:55:15 +0300 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2023-04-12 12:32:57 -0400 |
| commit | ebd8918b7c50ae51921664e24fac0de4376ffcf9 (patch) | |
| tree | 39f7112ed74735163f2208abe7e491bdbdaad757 /libraries/template-haskell/Language/Haskell/TH/Ppr.hs | |
| parent | ecf22da3c6d992d76fbb8e970b4ffbabb445d38a (diff) | |
| download | haskell-ebd8918b7c50ae51921664e24fac0de4376ffcf9.tar.gz | |
Allow generation of TTH syntax with TH
In other words allow generation of typed splices and brackets with
Untyped Template Haskell.
That is useful in cases where a library is build with TTH in mind,
but we still want to generate some auxiliary declarations,
where TTH cannot help us, but untyped TH can.
Such example is e.g. `staged-sop` which works with TTH,
but we would like to derive `Generic` declarations with TH.
An alternative approach is to use `unsafeCodeCoerce`, but then the
derived `Generic` instances would be type-checked only at use sites,
i.e. much later. Also `-ddump-splices` output is quite ugly:
user-written instances would use TTH brackets, not `unsafeCodeCoerce`.
This commit doesn't allow generating of untyped template splices
and brackets with untyped TH, as I don't know why one would want to do
that (instead of merging the splices, e.g.)
Diffstat (limited to 'libraries/template-haskell/Language/Haskell/TH/Ppr.hs')
| -rw-r--r-- | libraries/template-haskell/Language/Haskell/TH/Ppr.hs | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/libraries/template-haskell/Language/Haskell/TH/Ppr.hs b/libraries/template-haskell/Language/Haskell/TH/Ppr.hs index 034d2687b3..dbe3cb85df 100644 --- a/libraries/template-haskell/Language/Haskell/TH/Ppr.hs +++ b/libraries/template-haskell/Language/Haskell/TH/Ppr.hs @@ -232,6 +232,8 @@ pprExp _ (LabelE s) = text "#" <> text s pprExp _ (ImplicitParamVarE n) = text ('?' : n) pprExp _ (GetFieldE e f) = pprExp appPrec e <> text ('.': f) pprExp _ (ProjectionE xs) = parens $ hcat $ map ((char '.'<>) . text) $ toList xs +pprExp _ (TypedBracketE e) = text "[||" <> ppr e <> text "||]" +pprExp _ (TypedSpliceE e) = text "$$" <> pprExp appPrec e pprFields :: [(Name,Exp)] -> Doc pprFields = sep . punctuate comma . map (\(s,e) -> pprName' Applied s <+> equals <+> ppr e) |