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Fix issue with unparenthesized patterns in pretty printed lambdas pointed out by @JoeyEremondi in #446

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Regarding the proposed fix in #446: The pattern pretty printer is
correct for cases where you just want the pattern, such as in
case-expressions. In some contexts, parentheses are required though, so
this fix addresses those places specifically.
This commit is contained in:
Evan Czaplicki 2014-01-14 16:27:06 +01:00
parent 6febb89fcd
commit 93321eca63
1 changed files with 7 additions and 6 deletions
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13
compiler/SourceSyntax/Expression.hs
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@ -111,8 +111,10 @@ instance Pretty def => Pretty (Expr' def) where
P.text "-" <> prettyParens e
Binop op e1 e2 -> P.sep [ prettyParens e1 <+> P.text op', prettyParens e2 ]
where op' = if Help.isOp op then op else "`" ++ op ++ "`"
Lambda p e -> let (ps,body) = collectLambdas (Location.none $ Lambda p e)
in P.text "\\" <> P.sep ps <+> P.text "->" <+> pretty body
Lambda p e -> P.text "\\" <> args <+> P.text "->" <+> pretty body
where
(ps,body) = collectLambdas (Location.none $ Lambda p e)
args = P.sep (map Pattern.prettyParens ps)
App _ _ -> P.hang func 2 (P.sep args)
where func:args = map prettyParens (collectApps (Location.none expr))
MultiIf branches -> P.text "if" $$ nest 3 (vcat $ map iff branches)
@ -179,12 +181,11 @@ collectApps lexpr@(Location.L _ expr) =
App a b -> collectApps a ++ [b]
_ -> [lexpr]
collectLambdas :: LExpr' def -> ([Doc], LExpr' def)
collectLambdas :: LExpr' def -> ([Pattern.Pattern], LExpr' def)
collectLambdas lexpr@(Location.L _ expr) =
case expr of
Lambda pattern body ->
let (ps, body') = collectLambdas body
in (pretty pattern : ps, body')
Lambda pattern body -> (pattern : ps, body')
where (ps, body') = collectLambdas body
_ -> ([], lexpr)
prettyParens :: (Pretty def) => LExpr' def -> Doc