Non-ASCII type names get garbled when their `TypeRep` is shown (#14925) · Issues · Glasgow Haskell Compiler / GHC

Non-ASCII type names get garbled when their `TypeRep` is shown

Typeable allows easily showing the name of a type by, well, using show on it. However, this does not work right for types with Unicode symbols in their name:

GHCi, version 8.2.1: http://www.haskell.org/ghc/  :? for help
Prelude> :m +Data.Typeable
Prelude Data.Typeable> data W = W
Prelude Data.Typeable> typeOf W
W
Prelude Data.Typeable> data Ω = Ω
Prelude Data.Typeable> typeOf Ω
Î©

This did not yet happen in GHC-7:

GHCi, version 7.10.2: http://www.haskell.org/ghc/  :? for help
Prelude> :m +Data.Typeable
Prelude Data.Typeable> data W = W
Prelude Data.Typeable> typeOf W
W
Prelude Data.Typeable> data Ω = Ω
Prelude Data.Typeable> typeOf Ω
Ω

N.b.:

Prelude> import Data.ByteString.Char8 as BC8
Prelude BC8> BC8.putStrLn $ pack "Î©"
Ω

So, this appears to be a UTF-8 problem – something interprets bytestring-stored type-representation names as a different character encoding.

Trac metadata

Trac field	Value
Version	8.2.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	low
Resolution	Unresolved
Component	libraries/base
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

[Typeable](http://hackage.haskell.org/package/base-4.10.1.0/docs/Data-Typeable.html) allows easily showing the name of a type by, well, using `show` on it. However, this does not work right for types with Unicode symbols in their name:

```
GHCi, version 8.2.1: http://www.haskell.org/ghc/  :? for help
Prelude> :m +Data.Typeable
Prelude Data.Typeable> data W = W
Prelude Data.Typeable> typeOf W
W
Prelude Data.Typeable> data Ω = Ω
Prelude Data.Typeable> typeOf Ω
Î©
```

This did not yet happen in GHC-7:

```
GHCi, version 7.10.2: http://www.haskell.org/ghc/  :? for help
Prelude> :m +Data.Typeable
Prelude Data.Typeable> data W = W
Prelude Data.Typeable> typeOf W
W
Prelude Data.Typeable> data Ω = Ω
Prelude Data.Typeable> typeOf Ω
Ω
```

N.b.:

So, this appears to be a UTF-8 problem – something interprets bytestring-stored type-representation names as a different character encoding.

<details><summary>Trac metadata</summary>

| Trac field             | Value          |
| ---------------------- | -------------- |
| Version                | 8.2.1          |
| Type                   | Bug            |
| TypeOfFailure          | OtherFailure   |
| Priority               | low            |
| Resolution             | Unresolved     |
| Component              | libraries/base |
| Test case              |                |
| Differential revisions |                |
| BlockedBy              |                |
| Related                |                |
| Blocking               |                |
| CC                     |                |
| Operating system       |                |
| Architecture           |                |

</details>