ide-backend drives the GHC API to build, query, and run your code. It handles the tricky bits of driving the GHC API for use with integrated development environments. It was originally developed for the School of Haskell and FP Haskell Center, and is now an open source project. With stack-ide, IDEs and text editors can talk to ide-backend with a JSON protocol.
stack is required to
build ide-backend. Once you have stack, run stack install.
To run the tests, stack build ide-backend-server && stack test.
This won't run a complete test, as it will only use your current GHC
version, but that should be sufficient for most development. We can
leave it to travis to try
multiple GHC versions.
Note: Hopefully soon this will merely be stack test. See
this issue.
The following simple example demonstrates basic usage of ide-backend.
{-# LANGUAGE OverloadedStrings #-}
import qualified Data.ByteString.Char8 as S8
import Data.Monoid ((<>))
import IdeSession
main :: IO ()
main = do
-- Initialization and providing some code
config <- sessionConfigFromEnv
sess <- initSession defaultSessionInitParams config
{ configLocalWorkingDir = Nothing }
let upd = updateSourceFile "Main.hs" "main = putStrLn \"Hello World\""
<> updateCodeGeneration True
<> updateGhcOpts ["-Wall"]
updateSession sess upd print -- print is used for progress updates
-- Print errors and warnings
errs <- getSourceErrors sess
mapM_ print errs
-- Run the code
ra <- runStmt sess "Main" "main"
let loop = do
res <- runWait ra
case res of
Left bs -> S8.putStr bs >> loop
Right rr -> putStrLn $ "Run result: " ++ show rr
loop
-- Get some type information
expTypes <- getExpTypes sess
print $ expTypes "Main" SourceSpan
{ spanFilePath = "Main.hs"
, spanFromLine = 1
, spanFromColumn = 8
, spanToLine = 1
, spanToColumn = 9
}
-- Autocompletion
autoCompletion <- getAutocompletion sess
print $ autoCompletion "Main" "putS"To run this, use stack runghc example.hs. The output should look
something like:
[1 of 1] Compiling Main
SourceError {errorKind = KindWarning, errorSpan = Main.hs@1:1-1:30, errorMsg = "Top-level binding with no type signature: main :: IO ()"}
Hello World
Run result: RunOk
[(Main.hs@1:8-1:16,"String -> IO ()"),(Main.hs@1:8-1:30,"IO ()")]
[putStr (VarName) defined in base-4.8.0.0:System.IO at <no location info> (home base-4.8.0.0:System.IO) (imported from base-4.8.0.0:Prelude at Main.hs@1:1-1:1),putStrLn (VarName) :: String -> IO () defined in base-4.8.0.0:System.IO at <no location info> (home base-4.8.0.0:System.IO) (imported from base-4.8.0.0:Prelude at Main.hs@1:1-1:1)]