X-Git-Url: https://git.lukelau.me/?a=blobdiff_plain;f=AST.hs;h=ae18a52347ce91c37336a06f891bae690ba691ec;hb=023adfd1ca927790be8335c0df3334a861129da3;hp=b57d7cb8cede024a9c2bb0e366d8d066474d331d;hpb=7527d7269557b5199bb1e661150ef958d97e2c15;p=kaleidoscope-hs.git

diff --git a/AST.hs b/AST.hs
index b57d7cb..ae18a52 100644
--- a/AST.hs
+++ b/AST.hs
@@ -4,10 +4,11 @@ import Data.Char
 import Text.Read 
 import Text.ParserCombinators.ReadP hiding ((+++), choice)
 
-data Expr = Num Float
+data Expr = Num Double
           | Var String
           | BinOp BinOp Expr Expr
           | Call String [Expr]
+          | If Expr Expr Expr
   deriving Show
 
 data BinOp = Add | Sub | Mul | Cmp Ordering
@@ -17,7 +18,10 @@ instance Read Expr where
   readPrec = parens $ choice [ parseNum
                              , parseVar
                              , parseCall
+                             , parseIf
                              , parseBinOp "<" 10 (Cmp LT)
+                             , parseBinOp ">" 10 (Cmp GT)
+                             , parseBinOp "==" 10 (Cmp EQ)
                              , parseBinOp "+" 20 Add
                              , parseBinOp "-" 20 Sub
                              , parseBinOp "*" 40 Mul
@@ -26,10 +30,7 @@ instance Read Expr where
           parseVar = Var <$> lift (munch1 isAlpha)
           parseBinOp s prc op = prec prc $ do
             a <- step readPrec
-            lift $ do
-              skipSpaces
-              string s
-              skipSpaces
+            spaced $ string s
             b <- readPrec
             return (BinOp op a b)
           parseCall = do
@@ -38,6 +39,15 @@ instance Read Expr where
                         sepBy (readS_to_P reads)
                               (skipSpaces >> char ',' >> skipSpaces)
             return (Call func params)
+          parseIf = do
+            spaced $ string "if" 
+            cond <- readPrec
+            spaced $ string "then"
+            thenE <- readPrec
+            spaced $ string "else"
+            elseE <- readPrec
+            return (If cond thenE elseE)
+          spaced f = lift $ skipSpaces >> f >> skipSpaces
             
 data Prototype = Prototype String [String]
   deriving Show