From 9f9f5c82ae4abd47727108b87118766f94423df0 Mon Sep 17 00:00:00 2001
From: Christian Rinderknecht <Christian.Rinderknecht@tezcore.com>
Date: Thu, 6 Feb 2020 12:32:23 +0100
Subject: [PATCH] Added an example about lambdas.

---
 .../docs/language-basics/functions.md         | 51 +++++++++++++++++++
 .../src/functions/incr_map.ligo               |  5 ++
 .../src/functions/incr_map.mligo              |  4 ++
 .../src/functions/incr_map.religo             |  4 ++
 4 files changed, 64 insertions(+)
 create mode 100644 gitlab-pages/docs/language-basics/src/functions/incr_map.ligo
 create mode 100644 gitlab-pages/docs/language-basics/src/functions/incr_map.mligo
 create mode 100644 gitlab-pages/docs/language-basics/src/functions/incr_map.religo

diff --git a/gitlab-pages/docs/language-basics/functions.md b/gitlab-pages/docs/language-basics/functions.md
index c43e5e33e..e68c93ed8 100644
--- a/gitlab-pages/docs/language-basics/functions.md
+++ b/gitlab-pages/docs/language-basics/functions.md
@@ -204,4 +204,55 @@ ligo evaluate-value gitlab-pages/docs/language-basics/src/functions/anon.religo
 # Outputs: 2
 ```
 
+<!--END_DOCUSAURUS_CODE_TABS-->
+
+If the example above seems contrived, here is a more common design
+pattern for lambdas: to be used as parameters to functions. Consider
+the use case of having a list of integers and mapping the increment
+function to all its elements.
+
+<!--DOCUSAURUS_CODE_TABS-->
+<!--Pascaligo-->
+```pascaligo group=c
+function incr_map (const l : list (int)) : list (int) is
+  list_map (function (const i : int) : int is i + 1, l)
+```
+You can call the function `incr_map` defined above using the LIGO compiler
+like so:
+```shell
+ligo run-function
+gitlab-pages/docs/language-basics/src/functions/incr_map.ligo incr_map
+"list [1;2;3]"
+# Outputs: [ 2 ; 3 ; 4 ]
+```
+
+<!--Cameligo-->
+```cameligo group=c
+let incr_map (l : int list) : int list =
+  List.map (fun (i : int) -> i + 1) l
+```
+You can call the function `incr_map` defined above using the LIGO compiler
+like so:
+```shell
+ligo run-function
+gitlab-pages/docs/language-basics/src/functions/incr_map.mligo incr_map
+"list [1;2;3]"
+# Outputs: [ 2 ; 3 ; 4 ]
+```
+
+<!--Reasonligo-->
+```reasonligo group=c
+let incr_map = (l : list (int)) : list (int) =>
+  List.map ((i : int) => i + 1, l);
+```
+You can call the function `incr_map` defined above using the LIGO compiler
+like so:
+```shell
+ligo run-function
+gitlab-pages/docs/language-basics/src/functions/incr_map.religo incr_map
+"list [1;2;3]"
+# Outputs: [ 2 ; 3 ; 4 ]
+```
+
+
 <!--END_DOCUSAURUS_CODE_TABS-->
diff --git a/gitlab-pages/docs/language-basics/src/functions/incr_map.ligo b/gitlab-pages/docs/language-basics/src/functions/incr_map.ligo
new file mode 100644
index 000000000..e5f915847
--- /dev/null
+++ b/gitlab-pages/docs/language-basics/src/functions/incr_map.ligo
@@ -0,0 +1,5 @@
+function increment (const b : int) : int is
+   (function (const a : int) : int is a + 1) (b)
+
+function incr_map (const l : list (int)) : list (int) is
+  list_map (function (const i : int) : int is i + 1, l)
diff --git a/gitlab-pages/docs/language-basics/src/functions/incr_map.mligo b/gitlab-pages/docs/language-basics/src/functions/incr_map.mligo
new file mode 100644
index 000000000..b2dd363c8
--- /dev/null
+++ b/gitlab-pages/docs/language-basics/src/functions/incr_map.mligo
@@ -0,0 +1,4 @@
+let increment (b : int) : int = (fun (a : int) -> a + 1) b
+
+let incr_map (l : int list) : int list =
+  List.map (fun (i : int) -> i + 1) l
diff --git a/gitlab-pages/docs/language-basics/src/functions/incr_map.religo b/gitlab-pages/docs/language-basics/src/functions/incr_map.religo
new file mode 100644
index 000000000..85b8a39f4
--- /dev/null
+++ b/gitlab-pages/docs/language-basics/src/functions/incr_map.religo
@@ -0,0 +1,4 @@
+let increment = (b : int) : int => ((a : int) : int => a + 1)(b);
+
+let incr_map = (l : list (int)) : list (int) =>
+  List.map ((i : int) => i + 1, l);