Template Haskell: Splicing Infinite Syntax Tree doesn't stop

[guest]

Splicing an infinite syntax tree causes compile-time infinite loop.

e.g.

{-# LANGUAGE TemplateHaskell #-}
import Data.Function
$(fix id)

doesn't stop.

[igloo]

That's the expected behaviour. The splice is a program that is run at compile-time, so if it doesn't terminate then neither will compilation.

[shelarcy]

Replying to igloo:

That's the expected behaviour. The splice is a program that is run at compile-time, so if it doesn't terminate then neither will compilation.

Really?

GHC can check infinite loop with no action when we use compiled program.

import Data.Function
main = fix id

$ ghc --make Test.hs
[1 of 1] Compiling Main             ( Test.hs, Test.o )
Linking Test.exe ...

$ ./Test.exe
Test.exe: <<loop>>

But GHCi and Template Haskell does not.

Prelude Data.Function> fix id

So, Template Haskell doesn't report this error at compile time.

I think that it is the problem what guest want to fix.

[simonmar]

Thanks for the clarification; we already have a ticket for this: #2786