====== Racket Notes ==

The [[https://docs.racket-lang.org/reference/|Racket Reference]] has more details than this here page.  I took these notes regarding Racket as a memory aid to help me get started with Racket.

Racket identifiers can contain any characters except for whitespace and the following special characters: '''( ) [ ] { } " , ' ` ; # | \'''.  A special case is ''#'' which is allowed at the beginning of a symbol.


===== Data Structures ==

Linked lists are favored in racket.  Each element of the list can be a "pair" created by the ''cons'' function.  The first element of the pair is the current value and the second element of the pair is a pointer to the next pair or ''null''.

In Racket, ''null'' is an empty list, which is a singleton.


===== Common Constants ==

==== #t ==

The boolean true value.

==== #f == 

The boolean false value.

==== null ==

The empty list. 

===== Racket Functions ==

==== cons ==

Creates a newly allocated pair.

<code>
(cons <first-value> <second-value>)
</code>

==== car ==

Returns the first value of a pair created with ''cons''.

<code>
(car <pair-created-by-cons>)
</code>

==== cdr ==

Returns the second value of a pair created with ''cons''.

<code>
(cdr <par-created-by-cons>)
</code>

==== cond ==

It's somewhat like a switch statement in other languages:

<code>
  (cond 
    (<condition> <value-if-true>) 
    (<condition> <value-if-true>)... 
    (<value if false>))
</code>

==== string-append ==

Appends strings.  Arguments *must* be strings already.

<code>
(string-append <str1> <strN>...)
</code>

==== number->string ==

Converts a number to a string.

<code>
(number->string <number>)
</code>

==== list ==

Constructs a linked list from the specified arguments.

<code>
(list <arg1> <argN>...)
</code>

Note that the value returned is a pair containing the value of the first argument and pointer to the next pair in the list.