unused values should probably be a warning, not an error

[mwotton]

if you're developing bottom up, it's very distracting to see it flash red for variables you're not yet using. A warning is fine, but it shouldn't be an outright error.

[kazu-yamamoto]

Colors dependes on your environment. In my environment, "gray" is used. I don't configure colors at all. I created unused variables and typing "M-?" results in "warning", not "error". If unused variables are categorized to "error" in your environment, please give me example code.

[mwotton]

module Foo() where
killer = 10

gives

Line 2: 1 error(s), 2 warning(s)
 Warning: Defined but not used: `killer'
Warning: Definition but no type signature for `killer'
         Inferred type: killer :: t

Warning: Defaulting the following constraint(s) to type `Integer'
         `Num t' arising from the literal `10' at foo.hs:2:9-10
In the expression: 10
In the definition of `killer': killer = 10

[kazu-yamamoto]

I don't understand your point, sorry. This result seems natural to me. What is your problem?

[mwotton]

I'm trying to work out what the error is - it says "Line 2: 1 error, 2 warnings", but there are only two warnings listed, no errors.

[mwotton]

Three warnings, I mean:) but no errors.

[kazu-yamamoto]

OK. I understand.
P.S.
Since I found ghc-mod does not work with GHC 6.12, I'm suffering from this bug now.

http://hackage.haskell.org/trac/ghc/ticket/4015

[mwotton]

really? But I don't have any records in that test program...

[kazu-yamamoto]

Really? What's version of GHC? I'm using GHC 6.12.1.

[mwotton]

I'm using 6.12.1 too. The output from ghc-mod actually looks reasonable, I think it's just getting processed somewhere in the elisp.

mwotton@loki:/home/mwotton/projects$ ghc-mod check ./foo.hs
foo.hs:3:0:Warning: Definition but no type signature for `res'         Inferred type: res::t
foo.hs:3:6:Warning: Defaulting the following constraint(s) to type `Integer'         `Num t' arising from the literal `20' at foo.hs:3:6-7In the expression: 20In the definition of `res': res = 20
foo.hs:4:0: Warning: Defined but not used: `killer'
foo.hs:4:0:Warning: Definition but no type signature for `killer'         Inferred type: killer :: t
foo.hs:4:9:Warning: Defaulting the following constraint(s) to type `Integer'         `Num t' arising from the literal `10' at foo.hs:4:9-10In the expression: 10In the definition of `killer': killer = 10
Warning: output was redirected with -o, but no output will be generated

because there is no Main module.

[kazu-yamamoto]

This bug is relating to "browse" not "check".

[kazu-yamamoto]

In my environment, 3 warnings are displayed...

[mwotton]

right, this looks great now. THanks!