About

Lists are somewhat like an array or a hash from other programming languages. However, lists in Mythryl are items of all the same type. A Mythryl list would be all String, all Int, etc.

Defining a list

This is a string:

string =  "abc";

This is a list of strings:

list =  [ "abc", "def" ];

strcat() - Displaying a list

Taking our list of strings:

list =  [ "abc", "def" ];

You cannot output that list with printf "%s\n" list; because printf expects a string.

To use printf, the list needs to be turned into a string using strcat().

printf "%s\n" ( strcat( [ "abc", "def" ] ) );
# =>
# abcdef

Variables can be used in the usual ways:

list =  [ "abc", "def" ];
printf "%s\n" ( strcat( list ) );
# =>
# abcdef

a =  "abc";
b =  "def";
list =  [ a, b ];
printf "%s\n" ( strcat( list ) );
# =>
# abcdef

`apply` - Displaying a list (properly)

While strcat() can be used to display a list, apply can display a list more neatly.

apply iterates through a list, applying a function to each element. In this example, printf is applied individually to each element.

list =  [ "test", "list" ];
apply  printf "'%s'\n" list;
# =>
# 'test'
# 'list'

In the above example, each element is encapsulated by single quotes ( ' ) and separated by a newline ( \n ).

map

map applies a function to each element of a list.

Unlike apply, map builds a return list. This lets us assign the return list to a named value.

list =  [ "abc", "def" ];
list =  map  toupper( list );
apply  printf "'%s'\n" list;
# =>
# 'ABC'
# 'DEF'

! - Prepending to a list

Prepending a string to a list is done with the exclamation point ( ! ).

list =  [ "def", "ghi" ];
list =  "abc" ! list;
apply  printf "'%s'\n" list;
# =>
# 'abc'
# 'def'
# 'ghi'

A list must have elements that are all the same type, so you cannot prepend a different type. For example, you cannot prepend an Int to a list of Strings.

@ - Combining lists

Where + (plus) combines strings together and ! (exclamation point) prepends a string to a list, @ (at) combines lists together.

a =  [ "one", "two" ];
b =  [ "three", "four" ];
list =  a @ b;
apply  printf "'%s'\n" list;
# =>
# 'one'
# 'two'
# 'three'
# 'four'

Built-in functions, on lists

Various other functions will work on lists.

reverse()

Reverses each element. Note that this does not reverse any of the contents within the elements.

list =  [ "abc", "def", "ghi" ];
list =  reverse( list );
apply  printf "'%s'\n" list;
# =>
# 'ghi'
# 'def'
# 'abc'

head()

head() returns the first element of a list.

list =  [ "abc", "def", "ghi" ];
string =  head( a );
printf "%s\n" ( string );
# =>
# abc

Note that you don't need (and can't use) strcat() in this case. head() expects a list (of strings), and returns a String.

tail()

tail() returns a list of everything after the first element.

list =  [ "abc", "def", "ghi" ];
list =  tail( list );
apply  printf "'%s'\n" list;
# =>
# 'ghi'

strsort()

strsort() sorts a list of strings.

list =  [ "ghi", "abc", "def" ];
list =  strsort( list );
apply  printf "'%s'\n" list;
# =>
# 'abc'
# 'def'
# 'ghi'

struniqsort()

struniqsort() is similar to strsort() will drop any duplicate strings.

list =  [ "ghi", "abc", "def", "abc", "def", "ghi", "def" ];
list =  struniqsort( a );
apply  printf "'%s'\n" list;
# =>
# 'abc'
# 'def'
# 'ghi'

shuffle()

Makes a list pseudo-randomized.

list =  [ "a", "b", "c", "d", "e", "f", "g", "h", "i" ];
list =  shuffle( a );
string =  strcat( list );
printf "%s\n" string;
# =>
# *

* Pseudo-randomized. Perhaps dbehicgfa.

length()

Where strlen() gives the length of a string, length(), counts the number of elements in an array.

a = [ "abc", "def", "ghi" ];
a = length( a );
printf "%d\n" a;
# =>
# 3

More list functions

[1] The standard list API

From the documentation, we can see the description for tail()

tail : list(X ) -> list(X );

tail() accepts a list, and returns a list.