Haskell: steps 0-3

1 files changed, 28 insertions, 0 deletions

diff --git a/haskell/step0_repl.hs b/haskell/step0_repl.hs
new file mode 100644
index 0000000..d944263
--- /dev/null
+++ b/haskell/step0_repl.hs
@@ -0,0 +1,28 @@
+import System.IO (hGetLine, hFlush, hIsEOF, stdin, stdout)
+import Control.Monad
+
+-- read
+mal_read str = str
+
+-- eval
+eval ast env = ast
+
+-- print
+mal_print exp = exp
+
+-- repl
+rep line = mal_print $ eval (mal_read line) ""
+
+repl_loop = do
+    putStr "user> "
+    hFlush stdout
+    ineof <- hIsEOF stdin
+    when (not ineof) $ do
+        line <- hGetLine stdin
+        if null line
+            then repl_loop
+            else do
+                putStrLn $ rep line
+                repl_loop
+
+main = repl_loop