forth: Move hints to HINTS.md

exercises/forth/HINTS.md

@@ -0,0 +1,12 @@
+## Hints
+
+To complete this exercise, you need to create the data type `ForthState`
+and implement the following functions:
+
+- `empty` returns an empty `ForthState`.
+- `evalText` evaluates an input Text, returning the new state.
+- `formatStack` returns the current stack as Text, with the element on top
+of the stack being the rightmost element in the output
+
+You will find the type signatures already in place, but it is up to you
+to define the functions.

exercises/forth/src/Forth.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE OverloadedStrings #-}
+
 module Forth
   ( ForthError(..)
   , ForthState
@@ -9,8 +10,6 @@ module Forth
 
 import Data.Text (Text)
 
-data ForthState -- TODO: define this data type
-
 data ForthError
      = DivisionByZero
      | StackUnderflow
@@ -19,13 +18,10 @@ data ForthError
      deriving (Show, Eq)
 
 empty :: ForthState
-empty = error "TODO: An empty ForthState"
+empty = undefined
 
 evalText :: Text -> ForthState -> Either ForthError ForthState
-evalText = error "TODO: Evaluate an input Text, returning the new state"
+evalText = undefined
 
 formatStack :: ForthState -> Text
-formatStack = error "TODO: Return the current stack as Text with the element \
-                    \on top of the stack being the rightmost element in the \
-                    \output"
-
+formatStack = undefined