From a2ca938714fa7a7892433d5de356f81c23ed7741 Mon Sep 17 00:00:00 2001 From: Jack Firth Date: Mon, 6 Jul 2015 17:03:10 -0700 Subject: [PATCH] Update README.md --- README.md | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/README.md b/README.md index 0e24255..faaf4b9 100644 --- a/README.md +++ b/README.md @@ -2,4 +2,6 @@ lenses [![Build Status](https://travis-ci.org/jackfirth/lenses.svg?branch=master =================================== [Documentation](http://pkg-build.racket-lang.org/doc/lenses/index.html) -A Racket package for creating and composing pure functional lenses. A lens is a function that examines a small subpiece of some larger structure. When given a value of that larger structure, the lens returns two values: a *view* value, which is the subpiece, and a *context* function, which accepts a new view value and returns a new structure with the old view replaced by the new view. Think of them as composable, pure functional getters and setters. Examples can be found in the documentation. +A Racket package for creating and composing pure functional lenses. + +A lens is a value that can be used to focus on a small subpiece of some larger structure. Given a lens and a value of that larger structure, two values can be dervied: a *view* value, which is the subpiece, and a *context* function, which accepts a new view value and returns a new structure with the old view replaced by the new view. Think of them as composable, pure functional getters and setters. Examples can be found in the documentation.