4 files changed, 125 insertions, 7 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md
index cb9b0da..61ae7eb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,8 @@
 
 - The `iterator` module gains the `first` and `at` functions.
 - The `list` module renames the `head` and `tail` functions to `first` and `rest`.
+- `int.to_base_string` now returns a `Result(Int, InvalidBase)`.
+- The `int` module gains the `to_base2`, `to_base8`, `to_base16` and `to_base36` functions.
 
 ## v0.17.1 - 2021-09-15
 
diff --git a/src/gleam/int.gleam b/src/gleam/int.gleam
index 0df7397..6c280d6 100644
--- a/src/gleam/int.gleam
+++ b/src/gleam/int.gleam
@@ -62,21 +62,37 @@ if javascript {
     "../gleam_stdlib.js" "to_string"
 }
 
+/// For use in to_base_string when base is outside of the allowed range.
+pub type InvalidBase {
+  InvalidBase
+}
+
 /// Prints a given int to a string using the base number provided.
+/// Supports only bases 2 to 36, for values outside of which this function returns an Error(InvalidBase).
+/// For common bases (2, 8, 16, 36), use the to_baseN functions.
 ///
 /// ## Examples
 ///
 ///    > to_base_string(2, 2)
-///    "10"
+///    Ok("10")
 ///
 ///    > to_base_string(48, 16)
-///    "30"
+///    Ok("30")
 ///
 ///    > to_base_string(48, 36)
-///    "1C"
+///    Ok("1C")
 ///
-pub fn to_base_string(int, base) {
-  do_to_base_string(int, base)
+///    > to_base_string(48, 1)
+///    Error(InvalidBase)
+///
+///    > to_base_string(48, 37)
+///    Error(InvalidBase)
+///
+pub fn to_base_string(int, base) -> Result(String, InvalidBase) {
+  case base >= 2 && base <= 36 {
+    True -> Ok(do_to_base_string(int, base))
+    False -> Error(InvalidBase)
+  }
 }
 
 if erlang {
@@ -89,6 +105,50 @@ if javascript {
     "../gleam_stdlib.js" "int_to_base_string"
 }
 
+/// Prints a given int to a string using base2.
+///
+/// ## Examples
+///
+///    > to_base2(2)
+///    "10"
+///
+pub fn to_base2(int) {
+  do_to_base_string(int, 2)
+}
+
+/// Prints a given int to a string using base8.
+///
+/// ## Examples
+///
+///    > to_base8(15)
+///    "17"
+///
+pub fn to_base8(int) {
+  do_to_base_string(int, 8)
+}
+
+/// Prints a given int to a string using base16.
+///
+/// ## Examples
+///
+///    > to_base16(48)
+///    "30"
+///
+pub fn to_base16(int) {
+  do_to_base_string(int, 16)
+}
+
+/// Prints a given int to a string using base16.
+///
+/// ## Examples
+///
+///    > to_base36(48)
+///    "1C"
+///
+pub fn to_base36(int) {
+  do_to_base_string(int, 36)
+}
+
 /// Takes an int and returns its value as a float
 ///
 /// ## Examples
diff --git a/src/gleam_stdlib.js b/src/gleam_stdlib.js
index 158a571..96fa4f1 100644
--- a/src/gleam_stdlib.js
+++ b/src/gleam_stdlib.js
@@ -54,7 +54,7 @@ export function float_to_string(float) {
 }
 
 export function int_to_base_string(int, base) {
-  return int.toString(base);
+  return int.toString(base).toUpperCase();
 }
 
 export function string_replace(string, target, substitute) {
diff --git a/test/gleam/int_test.gleam b/test/gleam/int_test.gleam
index bec9624..07832dd 100644
--- a/test/gleam/int_test.gleam
+++ b/test/gleam/int_test.gleam
@@ -70,11 +70,67 @@ pub fn parse_test() {
 pub fn to_base_string_test() {
   100
   |> int.to_base_string(16)
-  |> should.equal("64")
+  |> should.equal(Ok("64"))
 
   -100
   |> int.to_base_string(16)
+  |> should.equal(Ok("-64"))
+
+  100
+  |> int.to_base_string(1)
+  |> should.equal(Error(int.InvalidBase))
+
+  100
+  |> int.to_base_string(37)
+  |> should.equal(Error(int.InvalidBase))
+}
+
+pub fn to_base2_test() {
+  100
+  |> int.to_base2()
+  |> should.equal("1100100")
+
+  -100
+  |> int.to_base2()
+  |> should.equal("-1100100")
+}
+
+pub fn to_base8_test() {
+  100
+  |> int.to_base8()
+  |> should.equal("144")
+
+  -100
+  |> int.to_base8()
+  |> should.equal("-144")
+}
+
+pub fn to_base16_test() {
+  100
+  |> int.to_base16()
+  |> should.equal("64")
+
+  -100
+  |> int.to_base16()
   |> should.equal("-64")
+
+  43981
+  |> int.to_base16()
+  |> should.equal("ABCD")
+
+  -43981
+  |> int.to_base16()
+  |> should.equal("-ABCD")
+}
+
+pub fn to_base36_test() {
+  100
+  |> int.to_base36()
+  |> should.equal("2S")
+
+  -100
+  |> int.to_base36()
+  |> should.equal("-2S")
 }
 
 pub fn to_float_test() {