diff --git a/fib.roc b/fib.roc
index b5b8192..809d149 100644
--- a/fib.roc
+++ b/fib.roc
@@ -5,8 +5,8 @@ app "fibonacci"
 
 main : Task.Task {} I32
 main =
-    numStrings = 
-        List.range {start: At 0u128, end: At 186u128} # 186 is all we can do with 128 bit
+    numStrings =
+        List.range { start: At 0u128, end: At 186u128 } # 186 is all we can do with 128 bit
         |> List.walk [] fibWalk
         |> List.map Num.toStr
         |> Str.joinWith "\n"
@@ -15,9 +15,10 @@ main =
 
 fibWalk : List (Num a), Num a -> List (Num a)
 fibWalk = \l, n ->
-    next = when l is
-        [] | [_] -> fib n
-        [.., a, b] -> a + b
+    next =
+        when l is
+            [] | [_] -> fib n
+            [.., a, b] -> a + b
     List.append l next
 
 fib : Num a -> Num a
diff --git a/justfile b/justfile
new file mode 100644
index 0000000..ea5e97b
--- /dev/null
+++ b/justfile
@@ -0,0 +1,13 @@
+set shell := ["nu", "-c"]
+
+default:
+	print "Select a command"
+
+dev target +FLAGS="": (build target FLAGS)
+	if ('out/{{target}}' | path exists) { out/{{target}} } else { ^$"out/('{{target}}' | str replace -r '\.roc$' '')" }
+
+build target +FLAGS="--optimize": init
+	roc build {{FLAGS}} ('{{target}}.roc' | str replace -r '\.roc\.roc$' '.roc') --output out/
+
+init:
+	mkdir out/
diff --git a/prime.roc b/prime.roc
index 6da8b91..fcb874c 100644
--- a/prime.roc
+++ b/prime.roc
@@ -5,8 +5,8 @@ app "prime"
 
 main : Task.Task {} I32
 main =
-    numStrings = 
-        List.range {start: At 0u64, end: At 1_000_000u64}
+    numStrings =
+        List.range { start: At 0u64, end: At 1_000_000u64 }
         |> List.map \e -> isPrimePre e
         |> List.walk [] primeWalk
         |> List.map Num.toStr
@@ -21,11 +21,13 @@ primeWalk = \l, n ->
     when n is
         Yes n2 ->
             List.append l n2
+
         Maybe n2 ->
             if isPrimePost l n2 then
                 List.append l n2
             else
                 l
+
         No _ -> l
 
 isPrimePre : U64 -> PrimeResult
@@ -34,23 +36,23 @@ isPrimePre = \n ->
         No n
     else if n < 4 then
         Yes n
-    else if ( firstPrimes |> List.any \p -> n > p && n % p == 0 ) then
+    else if (firstPrimes |> List.any \p -> n > p && n % p == 0) then
         No n
     else
         Maybe n
 
 isPrimePost : List U64, U64 -> Bool
 isPrimePost = \l, n ->
-    nFloat = (Num.toF64 n)
+    nFloat = Num.toF64 n
     valLimit = Num.ceiling (Num.sqrt nFloat)
     # approximate the number of primes < sqrt(n) to limit the range we have to check with a 25% error tolerance
     valLimitF = Num.toF64 valLimit
     limit = Num.ceiling (valLimitF * 1.25 / (Num.log valLimitF))
-    l 
-    |> List.sublist {start: 0, len: limit}
+    l
+    |> List.sublist { start: 0, len: limit }
     |> List.dropIf \p -> p > valLimit
     |> List.any \p -> n % p == 0
     |> Bool.not
 
-firstPrimes = 
+firstPrimes =
     [2, 3, 5, 7, 9, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 51, 67, 71, 73, 79, 83, 89, 97]