[FMFP] Interpreters

semester4/fmfp/code/00_syntax.hs

@@ -1,11 +1,17 @@
--- Declaring a function. Naming using lowerCamelCase
--- Arguments separated by whitespace
-myFunc :: Int -> Int -> Int
+-- Declaring a function. Naming using lowerCamelCase. Arguments separated by whitespace
+-- We can omit the parenthesis in the type (they show what compiler does)
+-- The below function uses guards (boolean checks)
+myFunc :: Int -> (Int -> Int)
 myFunc x y
   | x > 0 = x + y
   | x < 0 = -x + y
+  | otherwise = 0
 
--- On compile the above function is transformed like this:
--- TODO: Transform the template into correct version
-myFuncXCompiled :: Int -> Int
-myFuncXCompiled x = x
+-- If the checks are pattern-based, use pattern matching. _ is wildcard (any value)
+-- It is used when we don't need the variable. You can combine pattern-matching and guards
+myOtherFunc :: Int -> Int -> Int
+myOtherFunc 0 _ = 0
+myOtherFunc x 0 = x
+myOtherFunc x y
+  | x > 0 = x + y
+  | x < 0 = -x + y