Re: [Haskell-cafe] Display an inferred type during compilation

[Corentin Dupont]

Thanks all for your solutions!
Here is a summary:

- floating a value to the top level; then with -Wall GHC will give the type
since we didn't give a value,
- adding :: () to the value to check, GHC will complain equally,
- using TemplateHaskell (hereunder),
- waiting for the release of the next GHC with TypeHoles.

Corentin

On Sat, Apr 27, 2013 at 8:46 PM, Ilya Portnov port...@iportnov.ru wrote:

 **

 В письме от 27 апреля 2013 18:55:16 пользователь Corentin Dupont написал:

 Hi Cafe,
 can I ask the compiler to display the type of an inferred value during
 compile time?
 It would be great if I can output a string during compilation with the
 type.
 A little bit like running :type in GHCi, but without GHCi... Because
 running GHCi is sometime painful (I have to clean my code first).

 I'm thinking of something like:

 main :: IO ()
 main = do
a - someCode
displayTypeAtCompileTime a
return ()

 $ ghc -c test.hs
 test.hs:4:3: your type is: Foo

 Thanks,
 Corentin

 Hi.



 What about TemplateHaskell? Smth like:



 {-# LANGUAGE TemplateHaskell #-}

 module DisplayType where



 import Language.TH



 displayTypeAtCompileTime :: Name - Q Exp

 displayTypeAtComileTime name = do

 reified - reify name

 -- inspect reified structure, see TH haddock documentation

 runIO $ putStrLn $ show theType

 [| undefined |] -- you need to return some expression; since you are not
 to use it's value, it may be even undefined, it seems.



 ###



 {-# LANGUAGE TemplateHaskell #-}

 module Main where

 import DisplayType



 main = do

 ...

 $displayTypeAtCompileTime 'a

 ...







 WBR, Ilya Portnov.



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[Haskell-cafe] Display an inferred type during compilation

[Corentin Dupont]

Hi Cafe,
can I ask the compiler to display the type of an inferred value during
compile time?
It would be great if I can output a string during compilation with the type.
A little bit like running :type in GHCi, but without GHCi... Because
running GHCi is sometime painful (I have to clean my code first).

I'm thinking of something like:

main :: IO ()
main = do
   a - someCode
   displayTypeAtCompileTime a
   return ()

$ ghc -c test.hs
test.hs:4:3: your type is: Foo

Thanks,
Corentin
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Re: [Haskell-cafe] Display an inferred type during compilation

[Gwern Branwen]

On Sat, Apr 27, 2013 at 12:55 PM, Corentin Dupont
corentin.dup...@gmail.com wrote:
 can I ask the compiler to display the type of an inferred value during
 compile time?
 It would be great if I can output a string during compilation with the type.
 A little bit like running :type in GHCi, but without GHCi... Because running
 GHCi is sometime painful (I have to clean my code first).

You could try floating a value to the top level; then I believe -Wall
will make ghc print out the inferred type since you didn't give a type
signature.

-- 
gwern
http://www.gwern.net

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Re: [Haskell-cafe] Display an inferred type during compilation

[Ilya Portnov]

В письме от 27 апреля 2013 18:55:16 пользователь Corentin Dupont написал:


Hi Cafe,can I ask the compiler to display the type of an inferred value during 
compile 
time?It would be great if I can output a string during compilation with the 
type.A little 
bit like running :type in GHCi, but without GHCi... Because running GHCi is 
sometime 
painful (I have to clean my code first).

I'm thinking of something like:

main :: IO ()main = do   a - someCode   displayTypeAtCompileTime a   return ()

$ ghc -c test.hstest.hs:4:3: your type is: Foo

Thanks,Corentin


Hi.

What about TemplateHaskell? Smth like:

{-# LANGUAGE TemplateHaskell #-}
module DisplayType where

import Language.TH

displayTypeAtCompileTime :: Name - Q Exp
displayTypeAtComileTime name = do
reified - reify name
  -- inspect reified structure, see TH haddock documentation
runIO $ putStrLn $ show theType
 [| undefined |] -- you need to return some expression; since you are not 
to use it's 
value, it may be even undefined, it seems.

###

{-# LANGUAGE TemplateHaskell #-}
module Main where


import DisplayType

main = do
...
$displayTypeAtCompileTime 'a
...



WBR, Ilya Portnov.


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