runST

[Patrick Maier]

I have encountered a bug using the Hugs module STArray.
When reading in the following lines

> import STArray

> test :: ST s Int
> test = newArr (1,8) 0     >>= (\nums ->
>        writeArr nums 5 42 >>= (\_ ->
>        readArr nums 5     >>= (\v ->
>        return v)))

and then calling

runST test

Hugs 1.4 responds with

ERROR: Type error in encapsulation
*** expression     : runST test
*** term           : test
*** type           : ST a Int
*** does not match : ST b Int

Using Hugs 1.3 to do the same I get the expected result

42

I suspect there are bugs in type inference

Find them and kill them!

   Patrick Maier
   [EMAIL PROTECTED]