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Pretty-printing precedence issue #4068

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Blaisorblade opened this issue Mar 4, 2018 · 0 comments · Fixed by #4072
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Pretty-printing precedence issue #4068

Blaisorblade opened this issue Mar 4, 2018 · 0 comments · Fixed by #4072
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area:parser exp:novice

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@Blaisorblade
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Type (Int => Any) => List[Any] is shown without the parens:

scala> :type List(1, 2).map[T = Int]
Int => Any => List[Any]

while parens are omitted correctly here:

scala> val x: Int => (Int => Int) = _ => _ => 1
val x: Int => Int => Int = Lambda$1619/864078397@23310248

that is, the pretty-printer misses associativity of =>.
@Blaisorblade Blaisorblade self-assigned this Mar 4, 2018
Blaisorblade added a commit to dotty-staging/dotty that referenced this issue Mar 5, 2018
@Blaisorblade
Fix precedence in pretty-printing
580afc1 
WIP. I consider this a hack, though I haven't found the adequate test to show
it.
Fix scala#4068.
@Blaisorblade Blaisorblade mentioned this issue Mar 5, 2018
Merged
Blaisorblade added a commit to dotty-staging/dotty that referenced this issue Jul 30, 2018
@Blaisorblade
Fix precedence in pretty-printing
c3144e3 
WIP. I consider this a hack, though I haven't found the adequate test to show
it.
Fix scala#4068.
Blaisorblade added a commit to dotty-staging/dotty that referenced this issue Jul 30, 2018
@Blaisorblade
Fix scala#4068: Fix pretty-printing precedence for function types
6b85481 
Fix scala#4068 in a hacky way.
Blaisorblade added a commit to dotty-staging/dotty that referenced this issue Jul 30, 2018
@Blaisorblade
Fix scala#4068 properly
3817733 
`argText` will never add parentheses around its output, which makes sense for
arguments of type constructors: if we're printing `Foo[T1, T2]` we never
need parens around `T1` or `T2`, whatever its root operator.

But that's inappropriate for a function type `T1 => T2`; the code in
`toTextFunction` attempted to use `atPrec(InfixPrec)` to correct for that, but
that didn't work, because `argText` called `atPrec(GlobalPrec)` right away,
hence we ended up running
`atPrec(InfixPrec) { atPrec(GlobalPrec) { ... }}`, which means just
`atPrec(GlobalPrec) { ... }`.
Blaisorblade added a commit to dotty-staging/dotty that referenced this issue Aug 9, 2018
@Blaisorblade
Fix scala#4068: Fix pretty-printing precedence for function types
8d8dfff 
Using `atPrec(GlobalPrec)` ensures that `argText(args.head)` never adds
parentheses around its output, but that's inappropriate for a function type
`T1 => T2`. The nested calls to `atPrec` make no sense, but `argText` hid that
before it was refactored.
Jasper-M referenced this issue in Jasper-M/dotty Sep 27, 2018
@Blaisorblade
Merge pull request scala#4072 from dotty-staging/fix-#4068
da2a245 
Pretty-printing: handle type-operator precedence correctly
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Pretty-printing: handle type-operator precedence correctly dotty-staging/dotty
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