Day3 working

- Fix string and character encoding in output
- Fix autos not solving if another extends context

playground/samples/Prelude.newt

@@ -1,5 +1,7 @@
 module Prelude
 
+id : ∀ a. a → a
+id x = x
 
 data Bool : U where
   True False : Bool
@@ -15,6 +17,11 @@ _||_ : Bool → Bool → Bool
 True || _ = True
 False || b = b
 
+infixr 5 _&&_
+_&&_ : Bool → Bool → Bool
+False && b = False
+True && b = b
+
 infixl 6 _==_
 class Eq a where
   _==_ : a → a → Bool
@@ -23,6 +30,10 @@ data Nat : U where
   Z : Nat
   S : Nat -> Nat
 
+pred : Nat → Nat
+pred Z = Z
+pred (S k) = k
+
 instance Eq Nat where
   Z == Z = True
   S n == S m = n == m
@@ -73,7 +84,13 @@ infixr 2 _,_
 data _×_ : U → U → U where
   _,_ : ∀ A B. A → B → A × B
 
-infixl 6 _<_
+fst : ∀ a b. a × b → a
+fst (a,b) = a
+
+snd : ∀ a b. a × b → b
+snd (a,b) = b
+
+infixl 6 _<_ _<=_
 class Ord a where
   _<_ : a → a → Bool
 
@@ -82,6 +99,8 @@ instance Ord Nat where
   Z < S _ = True
   S n < S m = n < m
 
+_<=_ : ∀ a. {{Eq a}} {{Ord a}} → a → a → Bool
+a <= b = a == b || a < b
 -- Monad
 
 class Monad (m : U → U) where
@@ -95,6 +114,9 @@ ma >>= amb = bind ma amb
 _>>_ :  {0 m} {{Monad m}} {0 a b} -> m a -> m b -> m b
 ma >> mb = mb
 
+join : ∀ m. {{Monad m}} {0 a} → m (m a) → m a
+join mma = mma >>= id
+
 -- Equality
 
 infixl 1 _≡_
@@ -167,7 +189,6 @@ instance Mul Nat where
   Z * _ = Z
   S n * m = m + n * m
 
-
 infixl 7 _-_
 class Sub a where
   _-_ : a → a → a
@@ -189,6 +210,17 @@ pfunc sconcat : String → String → String := `(x,y) => x + y`
 instance Concat String where
   _++_ = sconcat
 
+
+pfunc jsEq uses (True False) : ∀ a. a → a → Bool := `(_, a, b) => a == b ? True : False`
+instance Eq Int where
+  a == b = jsEq a b
+
+instance Eq String where
+  a == b = jsEq a b
+
+instance Eq Char where
+  a == b = jsEq a b
+
 data Unit : U where
   MkUnit : Unit
 
@@ -306,9 +338,6 @@ instance Show Int where
 
 pfunc ord : Char -> Int := `(c) => c.charCodeAt(0)`
 
-infix 6 _<=_
-pfunc _<=_ uses (True False) : Int -> Int -> Bool := `(x,y) => (x <= y) ? True : False`
-
 pfunc unpack : String -> List Char
   := `(s) => {
     let acc = Nil(Char)
@@ -327,9 +356,15 @@ pfunc pack : List Char → String := `(cs) => {
 }
 `
 
-pfunc debugStr : ∀ a. a → String := `(_, obj) => {
+pfunc debugStr uses (natToInt listToArray) : ∀ a. a → String := `(_, obj) => {
   const go = (obj) => {
-    if (obj?.tag) {
+    if (obj?.tag === '_::_') {
+      let stuff = listToArray(undefined,obj)
+      return '['+(stuff.map(go).join(', '))+']'
+    }
+    if (obj?.tag === 'S') {
+      return ''+natToInt(obj)
+    } else if (obj?.tag) {
       let rval = '('+obj.tag
       for(let i=0;;i++) {
         let key = 'h'+i
@@ -398,3 +433,53 @@ span {a} f xs = go xs Nil
     go (x :: xs) left = if f x
       then go xs (x :: left)
       else (reverse left, x :: xs)
+
+instance Show Nat where
+  show n = show (natToInt n)
+
+enumerate : ∀ a. List a → List (Nat × a)
+enumerate {a} xs = go Z xs
+  where
+    go : Nat → List a → List (Nat × a)
+    go k Nil = Nil
+    go k (x :: xs) = (k,x) :: go (S k) xs
+
+filter : ∀ a. (a → Bool) → List a → List a
+filter pred Nil = Nil
+filter pred (x :: xs) = if pred x then x :: filter pred xs else filter pred xs
+
+drop : ∀ a. Nat -> List a -> List a
+drop _ Nil = Nil
+drop Z xs = xs
+drop (S k) (x :: xs) = drop k xs
+
+take : ∀ a. Nat -> List a -> List a
+take Z xs = Nil
+take _ Nil = Nil
+take (S k) (x :: xs) = x :: take k xs
+
+getAt : ∀ a. Nat → List a → Maybe a
+getAt _ Nil = Nothing
+getAt Z (x :: xs) = Just x
+getAt (S k) (x :: xs) = getAt k xs
+
+splitOn : ∀ a. {{Eq a}} → a → List a → List (List a)
+splitOn {a} v xs = go Nil xs
+  where
+    go : List a → List a → List (List a)
+    go acc Nil = reverse acc :: Nil
+    go acc (x :: xs) = if x == v
+      then reverse acc :: go Nil xs
+      else go (x :: acc) xs
+
+
+class Inhabited a where
+  default : a
+
+instance ∀ a. Inhabited (List a) where
+  default = Nil
+
+getAt! : ∀ a. {{Inhabited a}} → Nat → List a → a
+getAt! _ Nil = default
+getAt! Z (x :: xs) = x
+getAt! (S k) (x :: xs) = getAt! k xs