diff --git a/compiler/builtins/src/lib.rs b/compiler/builtins/src/lib.rs
index a7bd2f3fe8..92c095865a 100644
--- a/compiler/builtins/src/lib.rs
+++ b/compiler/builtins/src/lib.rs
@@ -2,4 +2,5 @@
 // See github.com/rtfeldman/roc/issues/800 for discussion of the large_enum_variant check.
 #![allow(clippy::large_enum_variant)]
 pub mod bitcode;
+pub mod standard_library;
 pub mod std;
diff --git a/compiler/builtins/src/standard_library.rs b/compiler/builtins/src/standard_library.rs
new file mode 100644
index 0000000000..996c0c0e82
--- /dev/null
+++ b/compiler/builtins/src/standard_library.rs
@@ -0,0 +1,28 @@
+use roc_module::symbol::ModuleId;
+
+#[inline(always)]
+pub fn module_source(module_id: ModuleId) -> &'static str {
+    match module_id {
+        ModuleId::RESULT => RESULT,
+        ModuleId::NUM => NUM,
+        ModuleId::STR => STR,
+        ModuleId::LIST => LIST,
+        ModuleId::DICT => DICT,
+        ModuleId::SET => SET,
+        ModuleId::BOX => BOX,
+        ModuleId::BOOL => BOOL,
+        _ => panic!(
+            "ModuleId {:?} is not part of the standard library",
+            module_id
+        ),
+    }
+}
+
+const RESULT: &str = include_str!("../standard_library/Result.roc");
+const NUM: &str = include_str!("../standard_library/Num.roc");
+const STR: &str = include_str!("../standard_library/Str.roc");
+const LIST: &str = include_str!("../standard_library/List.roc");
+const DICT: &str = include_str!("../standard_library/Dict.roc");
+const SET: &str = include_str!("../standard_library/Set.roc");
+const BOX: &str = include_str!("../standard_library/Box.roc");
+const BOOL: &str = include_str!("../standard_library/Bool.roc");
diff --git a/compiler/builtins/standard_library/Bool.roc b/compiler/builtins/standard_library/Bool.roc
new file mode 100644
index 0000000000..76b043c38d
--- /dev/null
+++ b/compiler/builtins/standard_library/Bool.roc
@@ -0,0 +1,10 @@
+Bool : [ True, False ]
+
+and : Bool, Bool -> Bool
+or : Bool, Bool -> Bool
+# xor : Bool, Bool -> Bool # currently unimplemented
+
+not : Bool -> Bool
+
+isEq : a, a -> Bool
+isNotEq : a, a -> Bool
diff --git a/compiler/builtins/standard_library/Box.roc b/compiler/builtins/standard_library/Box.roc
new file mode 100644
index 0000000000..8fd21bcf16
--- /dev/null
+++ b/compiler/builtins/standard_library/Box.roc
@@ -0,0 +1,11 @@
+box : a -> Box a
+unbox : Box a -> a
+
+# we'd need reset/reuse for box for this to be efficient
+# that is currently not implemented
+map : Box a, (a -> b) -> Box b
+map = \boxed, transform =
+    boxed
+        |> Box.unbox
+        |> transform
+        |> Box.box
diff --git a/compiler/builtins/standard_library/Dict.roc b/compiler/builtins/standard_library/Dict.roc
new file mode 100644
index 0000000000..e3b346cc86
--- /dev/null
+++ b/compiler/builtins/standard_library/Dict.roc
@@ -0,0 +1,13 @@
+empty : Dict k v
+single : k, v -> Dict k v
+get : Dict k v, k -> Result v [ KeyNotFound ]*
+walk : Dict k v, state, (state, k, v -> state) -> state
+insert : Dict k v, k, v -> Dict k v
+len : Dict k v -> Nat
+remove : Dict k v, k -> Dict k v
+contains : Dict k v, k -> Bool
+keys : Dict k v -> List k
+values : Dict k v -> List v
+union : Dict k v, Dict k v -> Dict k v
+intersection : Dict k v, Dict k v -> Dict k v
+difference : Dict k v, Dict k v -> Dict k v
diff --git a/compiler/builtins/standard_library/List.roc b/compiler/builtins/standard_library/List.roc
new file mode 100644
index 0000000000..19e490a2b3
--- /dev/null
+++ b/compiler/builtins/standard_library/List.roc
@@ -0,0 +1,71 @@
+isEmpty : List a -> Bool
+isEmpty = \list ->
+    List.len list == 0
+
+get : List a, Nat -> Result a [ OutOfBounds ]*
+set : List a, Nat, a -> List a
+replace : List a, Nat, a -> { list : List a, value : a }
+append : List a, a -> List a
+prepend : List a, a -> List a
+len : List a -> Nat
+concat : List a, List a -> List a
+last : List a -> Result a [ ListWasEmpty ]*
+single : a -> List a
+repeat : a, Nat -> List a
+reverse : List a -> List a
+join : List (List a) -> List a
+contains : List a, a -> Bool
+walk : List elem, state, (state, elem -> state) -> state
+walkBackwards  : List elem, state, (state, elem -> state) -> state
+walkUntil : List elem, state, (state, elem -> [ Continue state, Stop state ]) -> state
+
+sum : List (Num a) -> Num a
+sum = \list -> 
+    List.walk list 0 Num.add
+
+product : List (Num a) -> Num a
+product = \list -> 
+    List.walk list 1 Num.mul
+
+any : List a, (a -> Bool) -> Bool
+all : List a, (a -> Bool) -> Bool
+
+keepIf : List a, (a -> Bool) -> List a
+dropIf : List a, (a -> Bool) -> List a
+
+keepOks : List before, (before -> Result after *) -> List after
+keepErrs: List before, (before -> Result * after) -> List after
+map : List a, (a -> b) -> List b
+map2 : List a, List b, (a, b -> c) -> List c
+map3 : List a, List b, List c, (a, b, c -> d) -> List d
+map4 : List a, List b, List c, List d, (a, b, c, d -> e) -> List e
+mapWithIndex : List a, (a -> b) -> List b
+range : Int a, Int a -> List (Int a)
+sortWith : List a, (a, a -> [ LT, EQ, GT ] ) -> List a
+sortAsc : List (Num a) -> List (Num a)
+sortAsc = \list -> List.sortWith list Num.compare
+
+sortDesc : List (Num a) -> List (Num a)
+sortDesc = \list -> List.sortWith list (\a, b -> Num.compare b a)
+
+swap : List a, Nat, Nat -> List a
+
+first : List a -> Result a [ ListWasEmpty ]*
+
+dropFirst : List elem -> List elem
+dropLast : List elem -> List elem
+
+takeFirst : List elem, Nat -> List elem
+takeLast : List elem, Nat -> List elem
+
+drop : List elem, Nat -> List elem
+dropAt : List elem, Nat -> List elem
+
+min :  List (Num a) -> Result (Num a) [ ListWasEmpty ]*
+max :  List (Num a) -> Result (Num a) [ ListWasEmpty ]*
+
+joinMap : List a, (a -> List b) -> List b
+find : List elem, (elem -> Bool) -> Result elem [ NotFound ]*
+sublist : List elem, { start : Nat, len : Nat } -> List elem
+intersperse : List elem, elem -> List elem
+split : List elem, Nat -> { before: List elem, others: List elem }
diff --git a/compiler/builtins/standard_library/Num.roc b/compiler/builtins/standard_library/Num.roc
new file mode 100644
index 0000000000..42896b6b4a
--- /dev/null
+++ b/compiler/builtins/standard_library/Num.roc
@@ -0,0 +1,203 @@
+Num range : [ @Num range ]
+Int range : Num (Integer range) 
+Float range : Num (FloatingPoint range) 
+
+Signed128 : [ @Signed128 ]
+Signed64 : [ @Signed64 ]
+Signed32 : [ @Signed32 ]
+Signed16 : [ @Signed16 ]
+Signed8 : [ @Signed8 ]
+
+Unsigned128 : [ @Unsigned128 ]
+Unsigned64 : [ @Unsigned64 ]
+Unsigned32 : [ @Unsigned32 ]
+Unsigned16 : [ @Unsigned16 ]
+Unsigned8 : [ @Unsigned8 ]
+
+Natural : [ @Natural ]
+
+Integer range : [ @Integer range ]
+
+I128 : Num (Integer Signed128)
+I64 : Num (Integer Signed64)
+I32 : Num (Integer Signed32)
+I16 : Num (Integer Signed16)
+I8 : Int Signed8 
+
+U128 : Num (Integer Unsigned128)
+U64 : Num (Integer Unsigned64)
+U32 : Num (Integer Unsigned32)
+U16 : Num (Integer Unsigned16)
+U8 : Num (Integer Unsigned8)
+
+Nat : Num (Integer Natural)
+
+Decimal : [ @Decimal ]
+Binary64 : [ @Binary64 ]
+Binary32 : [ @Binary32 ]
+
+FloatingPoint range : [ @FloatingPoint range ]
+
+F64 : Num (FloatingPoint Binary64)
+F32 : Num (FloatingPoint Binary32)
+Dec : Num (FloatingPoint Decimal)
+
+# ------- Functions 
+
+toStr : Num * -> Str
+intCast : Int a -> Int b
+
+bytesToU16 : List U8, Nat -> Result U16 [ OutOfBounds ]
+bytesToU32 : List U8, Nat -> Result U32 [ OutOfBounds ]
+
+compare : Num a, Num a -> [ LT, EQ, GT ]
+
+isLt : Num a, Num a -> Bool
+isGt : Num a, Num a -> Bool
+isLte : Num a, Num a -> Bool
+isGte : Num a, Num a -> Bool
+
+isZero : Num a -> Bool
+
+isEven : Int a -> Bool
+isOdd : Int a -> Bool
+
+isPositive : Num a -> Bool
+isNegative : Num a -> Bool
+
+toFloat : Num * -> Float *
+
+abs : Num a -> Num a
+neg : Num a -> Num a
+
+add : Num a, Num a -> Num a
+sub : Num a, Num a -> Num a
+mul : Num a, Num a -> Num a
+
+sin : Float a -> Float a
+cos : Float a -> Float a
+tan : Float a -> Float a
+
+asin : Float a -> Float a
+acos : Float a -> Float a
+atan : Float a -> Float a
+
+sqrt : Float a -> Result (Float a) [ SqrtOfNegative ]*
+log : Float a -> Result (Float a) [ LogNeedsPositive ]*
+div : Float a, Float a -> Result (Float a) [ DivByZero ]*
+
+divCeil: Int a, Int a -> Result (Int a) [ DivByZero ]*
+divFloor: Int a, Int a -> Result (Int a) [ DivByZero ]*
+# mod : Float a, Float a -> Result (Float a) [ DivByZero ]*
+
+rem : Int a, Int a -> Result (Int a) [ DivByZero ]*
+# mod : Int a, Int a -> Result (Int a) [ DivByZero ]*
+isMultipleOf : Int a, Int a -> Bool
+
+bitwiseAnd : Int a, Int a -> Int a
+bitwiseXor : Int a, Int a -> Int a
+bitwiseOr : Int a, Int a -> Int a
+shiftLeftBy : Int a, Int a -> Int a
+shiftRightBy : Int a, Int a -> Int a
+shiftRightZfBy : Int a, Int a -> Int a
+
+round : Float * -> Int *
+floor : Float * -> Int *
+ceiling : Float * -> Int *
+
+pow : Float a, Float a -> Float a
+powInt : Int a, Int a -> Int a
+
+addWrap : Int range, Int range -> Int range
+addSaturated : Num a, Num a -> Num a
+addChecked : Num a, Num a -> Result (Num a) [ Overflow ]*
+
+subWrap : Int range, Int range -> Int range
+subSaturated : Num a, Num a -> Num a
+subChecked : Num a, Num a -> Result (Num a) [ Overflow ]*
+
+mulWrap : Int range, Int range -> Int range
+# mulSaturated : Num a, Num a -> Num a
+mulChecked : Num a, Num a -> Result (Num a) [ Overflow ]*
+
+minI8 : I8
+minI8 = -128i8
+
+maxI8 : I8
+maxI8 = 127i8
+
+minU8 : U8
+minU8 = 0u8
+
+maxU8 : U8
+maxU8 = 255u8
+
+minI16 : I16
+minI16 = -32768i16
+
+maxI16 : I16
+maxI16 = 32767i16
+
+minU16 : U16
+minU16 = 0u16
+
+maxU16 : U16
+maxU16 = 65535u16
+
+minI32 : I32
+minI32 = -2147483648
+
+maxI32 : I32
+maxI32 = 2147483647
+
+minU32 : U32
+minU32 = 0
+
+maxU32 : U32
+maxU32 = 4294967295
+
+minI64 : I64
+minI64 = -9223372036854775808
+
+maxI64 : I64
+maxI64 = 9223372036854775807
+
+minU64 : U64
+minU64 = 0
+
+maxU64 : U64
+maxU64 = 18446744073709551615
+
+minI128 : I128
+minI128 = -170141183460469231731687303715884105728
+
+maxI128 : I128
+maxI128 = 170141183460469231731687303715884105727
+
+minU128 : U128
+minU128 = 0
+
+maxU128 : U128
+maxU128 = 0340282366920938463463374607431768211455
+
+toI8 : Int * -> I8
+toI16 : Int * -> I16
+toI32 : Int * -> I32
+toI64 : Int * -> I64
+toI128 : Int * -> I128
+toU8 : Int * -> U8
+toU16 : Int * -> U16
+toU32 : Int * -> U32
+toU64 : Int * -> U64
+toU128 : Int * -> U128
+
+toI8Checked : Int * -> Result I8 [ OutOfBounds ]*
+toI16Checked : Int * -> Result I16 [ OutOfBounds ]*
+toI32Checked : Int * -> Result I32 [ OutOfBounds ]*
+toI64Checked : Int * -> Result I64 [ OutOfBounds ]*
+toI128Checked : Int * -> Result I128 [ OutOfBounds ]*
+toU8Checked : Int * -> Result U8 [ OutOfBounds ]*
+toU16Checked : Int * -> Result U16 [ OutOfBounds ]*
+toU32Checked : Int * -> Result U32 [ OutOfBounds ]*
+toU64Checked : Int * -> Result U64 [ OutOfBounds ]*
+toU128Checked : Int * -> Result U128 [ OutOfBounds ]*
diff --git a/compiler/builtins/standard_library/Result.roc b/compiler/builtins/standard_library/Result.roc
new file mode 100644
index 0000000000..46bb87d78c
--- /dev/null
+++ b/compiler/builtins/standard_library/Result.roc
@@ -0,0 +1,37 @@
+Result ok err : [ Ok ok, Err err ]
+
+isOk : Result ok err -> Bool
+isOk = \result ->
+    when result is
+        Ok _ -> True
+        Err _ -> False
+
+isErr : Result ok err -> Bool
+isErr = \result ->
+    when result is
+        Ok _ -> False
+        Err _ -> True
+
+withDefault : Result ok err, ok -> ok
+withDefault = \result, default ->
+    when result is
+        Ok value -> value
+        Err _ -> default
+
+map : Result a err, (a -> b) -> Result b err
+map = \result, transform ->
+    when result is
+        Ok v -> Ok (transform v)
+        Err e -> Err e
+
+mapErr : Result ok a, (a -> b) -> Result ok b
+mapErr = \result, transform ->
+    when result is
+        Ok v -> Ok v
+        Err e -> Err (transform e)
+
+after : Result a err, (a -> Result b err) -> Result b err
+after = \result, transform ->
+    when result is
+        Ok v -> transform v
+        Err e -> Err e
diff --git a/compiler/builtins/standard_library/Set.roc b/compiler/builtins/standard_library/Set.roc
new file mode 100644
index 0000000000..d3bc099f69
--- /dev/null
+++ b/compiler/builtins/standard_library/Set.roc
@@ -0,0 +1,20 @@
+empty : Set k
+single : k -> Set k
+insert : Set k, k -> Set k
+len : Set k -> Nat
+remove : Set k, k -> Set k
+contains : Set k, k -> Bool
+
+# toList = \set -> Dict.keys (toDict set)
+toList : Set k -> List k
+fromList : List k -> Set k
+
+union : Set k, Set k -> Set k
+intersection : Set k, Set k -> Set k
+difference : Set k, Set k -> Set k
+
+toDict : Set k -> Dict k {}
+
+walk : Set k, state, (state, k -> state) -> state
+walk = \set, state, step ->
+    Dict.walk (toDict set) state (\s, k, _ -> step s k)
diff --git a/compiler/builtins/standard_library/Str.roc b/compiler/builtins/standard_library/Str.roc
new file mode 100644
index 0000000000..b5c7baa52f
--- /dev/null
+++ b/compiler/builtins/standard_library/Str.roc
@@ -0,0 +1,50 @@
+Utf8ByteProblem :
+    [
+        InvalidStartByte,
+        UnexpectedEndOfSequence,
+        ExpectedContinuation,
+        OverlongEncoding,
+        CodepointTooLarge,
+        EncodesSurrogateHalf,
+    ]
+
+Utf8Problem : { byteIndex : Nat, problem : Utf8ByteProblem }
+
+isEmpty : Str -> Bool
+concat : Str, Str -> Str
+
+joinWith : List Str, Str -> Str
+split : Str, Str -> List Str
+repeat : Str, Nat -> Str
+countGraphemes : Str -> Nat
+startsWithCodePt : Str, U32 -> Bool
+
+toUtf8 : Str -> List U8
+
+# fromUtf8 : List U8 -> Result Str [ BadUtf8 Utf8Problem ]*
+# fromUtf8Range : List U8 -> Result Str [ BadUtf8 Utf8Problem Nat, OutOfBounds ]*
+
+fromUtf8 : List U8 -> Result Str [ BadUtf8 Utf8ByteProblem Nat ]*
+fromUtf8Range : List U8, { start : Nat, count : Nat } -> Result Str [ BadUtf8 Utf8ByteProblem Nat, OutOfBounds ]*
+
+startsWith : Str, Str -> Bool
+endsWith : Str, Str -> Bool
+
+trim : Str -> Str
+trimLeft : Str -> Str
+trimRight : Str -> Str
+
+toDec : Str -> Result Dec [ InvalidNumStr ]*
+toF64 : Str -> Result F64 [ InvalidNumStr ]*
+toF32 : Str -> Result F32 [ InvalidNumStr ]*
+toNat : Str -> Result Nat [ InvalidNumStr ]*
+toU128 : Str -> Result U128 [ InvalidNumStr ]*
+toI128 : Str -> Result I128 [ InvalidNumStr ]*
+toU64 : Str -> Result U64 [ InvalidNumStr ]*
+toI64 : Str -> Result I64 [ InvalidNumStr ]*
+toU32 : Str -> Result U32 [ InvalidNumStr ]*
+toI32 : Str -> Result I32 [ InvalidNumStr ]*
+toU16 : Str -> Result U16 [ InvalidNumStr ]*
+toI16 : Str -> Result I16 [ InvalidNumStr ]*
+toU8 : Str -> Result U8 [ InvalidNumStr ]*
+toI8 : Str -> Result I8 [ InvalidNumStr ]*