hsimport
A command line program for extending the import list of a Haskell source file.
hsimport gets the module name and the symbol name to import as arguments,
parses the given source file using the library haskell-src-exts and then tries
to only extend the import list if it's necessary. If the symbol is already
imported or if the whole module is already imported, then the given source file
isn't changed.
Installation
cabal install hsimport
Examples
$> hsimport -m 'Control.Monad' SomeSource.hs
=> import Control.Monad
$> hsimport -m 'Control.Monad' -s 'when' SomeSource.hs
=> import Control.Monad (when)
$> hsimport -m 'Control.Monad' -q 'CM' SomeSource.hs
=> import qualified Control.Monad as CM
$> hsimport -m 'Control.Monad' --as 'CM' SomeSource.hs
=> import Control.Monad as CM
$> hsimport -m 'Data.Maybe' -s 'Maybe'
=> import Data.Maybe (Maybe)
$> hsimport -m 'Data.Maybe' -s 'Maybe' -a
=> import Data.Maybe (Maybe(..))
$> hsimport -m 'Data.Maybe' -s 'Maybe' -w 'Just'
=> import Data.Maybe (Maybe(Just))
$> hsimport -m 'Data.Maybe' -s 'Maybe' -w 'Just' -w 'Nothing'
=> import Data.Maybe (Maybe(Just, Nothing))
Configuration
You can configure how the import declarations are pretty printed and where they're placed
by writing a configuration file like:
-- ~/.config/hsimport/hsimport.hs
import qualified Language.Haskell.Exts as HS
import HsImport
type HsImportDecl = HS.ImportDecl HS.SrcSpanInfo
main :: IO ()
main = hsimport $ defaultConfig { prettyPrint = prettyPrint, findImportPos = findImportPos }
where
-- This is a bogus implementation of prettyPrint, because it doesn't handle the
-- qualified import case nor does it considers any explicitely imported or hidden symbols.
prettyPrint :: HsImportDecl -> String
prettyPrint (HS.ImportDecl { HS.importModule = HS.ModuleName _ modName }) =
"import " ++ modName
-- This findImportPos implementation will always add the new import declaration
-- at the end of the current ones. The data type ImportPos has the two constructors
-- After and Before.
findImportPos :: HsImportDecl -> [HsImportDecl] -> Maybe ImportPos
findImportPos _ [] = Nothing
findImportPos newImport currentImports = Just . After . last $ currentImports
The position of the configuration file depends on the result of getUserConfigDir "hsimport",
which is a function from the package xdg-basedir,
on linux like systems it is ~/.config/hsimport/hsimport.hs.
If you've modified the configuration file, then the next call of hsimport will ensure a rebuild.
If you've installed hsimport with cabal install, without using a sandbox, then this should just work.
If you've build hsimport inside of a sandbox, then you most likely have to temporary modify the
GHC_PACKAGE_PATH for the next call of hsimport, to point ghc to the global database and
to the package database of the sandbox.
# global package database
$> export GLOBAL_PKG_DB=/usr/lib/ghc/package.conf.d/
# hsimport sandbox package database
$> export SANDBOX_PKG_DB=/home/you/hsimport-build-dir/.cabal-sandbox/*-packages.conf.d/
$> GHC_PACKAGE_PATH=$GLOBAL_PKG_DB:$SANDBOX_PKG_DB hsimport --help
Text Editor Integration
vim-hsimport
Command Line Usage
$> hsimport --help
hsimport [OPTIONS] [SOURCEFILE]
A command line program for extending the import list of a Haskell source
file.
Common flags:
-m --modulename=ITEM The module to import
-s --symbolname=ITEM The symbol to import, if empty, the entire module
is imported
-a --all All constructors or methods of the symbol should
be imported: 'Symbol(..)'
-w --with=ITEM The constructors or methods of the symbol
should be imported: 'Symbol(With)'
-q --qualifiedname=ITEM The name to use for a qualified module import
-o --outputsrcfile=FILE Save modified source file to file, if empty, the
source file is modified inplace
-h --help Display help message
-v --version Print version information
Issues
There is some rudimentarily handling for code using CPP, but the import statements
might be added at the wrong place, because the lines containing CPP directives
are ignored and therefore they aren't considered in the source line count.
