Permalink
Browse files

Lists.

  • Loading branch information...
1 parent 77abfd5 commit 8520d5ace96cc9162e3afea7de741ab0b712dd6a @sjl committed Oct 26, 2011
Showing with 156 additions and 1 deletion.
  1. +154 −0 chapters/35.markdown
  2. +1 −1 outline.org
  3. +1 −0 proofreader-volunteers.txt
View
@@ -0,0 +1,154 @@
+Lists
+=====
+
+We've worked a lot with variables so far, but we haven't talked about aggregates
+at all yet! Vim has two main aggregate types, and we'll look at the first now:
+lists.
+
+Vimscript lists are ordered, heterogeneous collections of elements. Run the
+following command:
+
+ :echo ['foo', 3, 'bar']
+
+Vim displays the list. Lists can of course be nested. Run the following
+command:
+
+ :echo ['foo', [3, 'bar']]
+
+Vim happily displays the list.
+
+Indexing
+--------
+
+Vimscript lists are zero-indexed, and you can get at the elements in the usual
+way. Run this command:
+
+ :echo [0, [1, 2]][1]
+
+Vim displays "[1, 2]". You can also index from the end of the list, much like
+Python. Try this command:
+
+ :echo [0, [1, 2]][-2]
+
+Vim displays `0`. The index `-1` refers to the last element in the list, `-2`
+is the second-to-last, and so on.
+
+Slicing
+-------
+
+Vim lists can also be sliced. This will *look* familiar to Python programmers,
+but it does *not* always act the same way! Run this command:
+
+ :echo ['a', 'b', 'c', 'd', 'e'][0:2]
+
+Vim displays "['a', 'b', 'c']" (elements 0, 1 and 2). You can safely exceed the
+upper bound as well. Try this command:
+
+ :echo ['a', 'b', 'c', 'd', 'e'][0:100000]
+
+Vim simply displays the entire list.
+
+Slice indexes can be negative. Try this command:
+
+ :echo ['a', 'b', 'c', 'd', 'e'][-2:-1]
+
+Vim displays "['d', 'e']" (elements -2 and -1).
+
+When slicing lists you can leave off the first index to mean "the beginning"
+and/or the last index to mean "the end". Run the following commands:
+
+ :echo ['a', 'b', 'c', 'd', 'e'][:1]
+ :echo ['a', 'b', 'c', 'd', 'e'][3:]
+
+Vim displays "['a', 'b']" and "['d', 'e']".
+
+Like Python, Vimscript allows you to index and slice strings too. Run the
+following command:
+
+ :echo "abcd"[0:2]
+
+Vim displays "abc".
+
+Concatenation
+-------------
+
+You can combine Vim lists with `+`. Try this command:
+
+ echo ['a', 'b'] + ['c']
+
+Vim, unsurprisingly, displays "['a', 'b', 'c']". There's not much else to say
+here -- Vimscript lists are surprisingly sane compared to the rest of the
+language.
+
+List Functions
+--------------
+
+Vim has a number of built-in functions for working with lists. Run these
+commands:
+
+ :let foo = ['a']
+ :call add(foo, 'b')
+ :echo foo
+
+Vim mutates the list `foo` in-place to append `'b'` and displays "['a', 'b']".
+Now run this command:
+
+ :echo len(foo)
+
+Vim displays "2", the length of the list. Try these commands:
+
+ :echo get(foo, 0, 'default')
+ :echo get(foo, 100, 'default')
+
+Vim displays "a" and "default". The `get` function will get the item at the
+given index from the given list, or return the given default value if the index
+is out of range in the list.
+
+Run this command:
+
+ :echo index(foo, 'b')
+ :echo index(foo, 'nope')
+
+Vim displays "1" and "-1". The `index` function returns the first index of the
+given item in the given list, or `-1` if the item is not in the list.
+
+Now run this command:
+
+ :echo join(foo)
+ :echo join(foo, '---')
+ :echo join([1, 2, 3], '')
+
+Vim displays "a b" and "a---b". `join` will join the items in the given list
+together into a string, separated by the given separator string (or a space if
+none is given), coercing each item to a string if necessary/possible.
+
+Run the following commands:
+
+ :call reverse(foo)
+ :echo foo
+ :call reverse(foo)
+ :echo foo
+
+Vim displays "['b', 'a']" and then "['a', 'b']". `reverse` reverses the given
+list *in place*.
+
+Exercises
+---------
+
+Read `:help List`. All of it. Notice the capital "L".
+
+Read `:help add()`.
+
+Read `:help len()`.
+
+Read `:help get()`.
+
+Read `:help index()`.
+
+Read `:help join()`.
+
+Read `:help reverse()`.
+
+Skim `:help functions` to find some other list-related functions I haven't
+mentioned yet. Run `:match Keyword /\clist/` to case-insensitively highlight
+the word "list" to make it easier to find what you're looking for.
View
@@ -32,7 +32,7 @@
** DONE execute normal!
** DONE basic regexes
** DONE Case Study: GrepMotion
-** TODO lists
+** DONE lists
** TODO looping
** TODO dictionaries
** TODO advanced regexes
@@ -4,3 +4,4 @@
@robhudson
@cemicolon
@execat
+@alesplin

0 comments on commit 8520d5a

Please sign in to comment.