Merge pull request #658 from sorki/fix/repline_0_4

Epic Support repline 0.4

.gitignore

@@ -12,3 +12,4 @@ ctags
 dist-newstyle
 result*
 .ghc.environment.*
+.hnixrc

README.md

@@ -32,6 +32,23 @@ $ env NIXPKGS_TESTS=yes PRETTY_TESTS=1 cabal v2-test
 $ ./dist/build/hnix/hnix --help
 ```
 
+## Using the REPL
+
+To enter the `hnix` REPL use
+
+```
+hnix --repl
+```
+
+To evaluate an expression and make it available in the REPL
+as the `input` variable use
+
+```
+hnix --eval -E '(import <nixpkgs> {}).pkgs.hello' --repl
+```
+
+Use the `:help` command for a list of all available REPL commands.
+
 ## Building with full debug info
 
 To build `hnix` for debugging, and with full tracing output and stack traces,

hnix.cabal

@@ -958,7 +958,7 @@ executable hnix
     , pretty-show
     , prettyprinter
     , ref-tf
-    , repline
+    , repline >= 0.4.0.0 && < 0.5
     , serialise
     , template-haskell
     , text

main/Main.hs

@@ -102,7 +102,12 @@ main = do
                   @(StdThunk (StandardT (StdIdT IO)))
                   frames
 
-      when (repl opts) $ withNixContext Nothing Repl.main
+      when (repl opts) $
+        if evaluate opts
+          then do
+            val <- Nix.nixEvalExprLoc mpath expr
+            withNixContext Nothing (Repl.main' $ Just val)
+          else withNixContext Nothing Repl.main
 
   process opts mpath expr
     | evaluate opts