From bac2d26f56770aa3612b87f358528e2e2daeda9e Mon Sep 17 00:00:00 2001
From: Louis Pilfold <louis@lpil.uk>
Date: Sun, 24 May 2020 22:53:24 +0100
Subject: io.{prinln, debug}

---
 src/gleam/io.gleam | 48 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/gleam/io.gleam b/src/gleam/io.gleam
index f4c1ad5..9fef99a 100644
--- a/src/gleam/io.gleam
+++ b/src/gleam/io.gleam
@@ -1,6 +1,6 @@
 external type DoNotLeak
 
-external fn erl_print(String) -> DoNotLeak =
+external fn erl_print(String, List(a)) -> DoNotLeak =
   "io" "fwrite"
 
 /// Writes a string to standard output.
@@ -8,10 +8,50 @@ external fn erl_print(String) -> DoNotLeak =
 /// ## Example
 ///
 ///    > io.print("Hi mum")
+///    // -> Hi mum
 ///    Nil
-///    //=> Hi mum
-///   
+///
 pub fn print(string: String) -> Nil {
-  erl_print(string)
+  erl_print(string, [])
+  Nil
+}
+
+/// Writes a string to standard output, appending a newline to the end.
+///
+/// ## Example
+///
+///    > io.println("Hi mum")
+///    // -> Hi mum
+///    Nil
+///
+pub fn println(string: String) -> Nil {
+  erl_print("~ts\n", [string])
+  Nil
+}
+
+/// Print a value to standard output using Erlang syntax.
+///
+/// The value is returned after being printed so it can be used in pipelines.
+///
+/// ## Example
+///
+///    > io.debug("Hi mum")
+///    // -> <<"Hi mum">>
+///    "Hi mum"
+///
+///    > io.debug(Ok(1))
+///    // -> {ok, 1}
+///    Ok(1)
+///
+///    > import list
+///    > [1, 2]
+///    > |> list.map(fn(x) { x + 1 })
+///    > |> io.debug
+///    > |> list.map(fn(x) { x * 2 })
+///    // -> [2, 3]
+///    [4, 6]
+///
+pub fn debug(term: anything) -> Nil {
+  erl_print("~tp\n", [term])
   Nil
 }
-- 
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