Certain do blocks cause TH to barf when ApplicativeDo is enabled
The following program fails with an error:
{-# LANGUAGE ApplicativeDo #-}
{-# LANGUAGE TemplateHaskell #-}
main = $([|do
return ()
return ()
return ()|])
Exotic.hs:4:12: error:
Exotic statement not (yet) handled by Template Haskell
[return ();
return (),
return ()]
It only happens when ApplicativeDo
is enabled.
Furthermore, while this example is extremely minimal, this issue isn’t restricted to ApplicativeDo
’s special handling of return
. The following example produces the same error:
{-# LANGUAGE ApplicativeDo #-}
{-# LANGUAGE TemplateHaskell #-}
main = $([|do
getLine
getLine
getLine|])
Exotic.hs:4:12: error:
Exotic statement not (yet) handled by Template Haskell
[getLine;
getLine,
getLine]
This doesn’t happen with fewer than three statements in the do
block, but it does happen with more.
Trac metadata
Trac field | Value |
---|---|
Version | 8.2.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Template Haskell |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |