% Erlang Cheat Sheet
% this is a comment
-module(cheat_sheet). % These are called "attributes" to your "module"
-behavior(behavior_name). % Optional, Includes A Standard "Behavior"
-export([data_types/1]).
-record(stuff,{a,b,c}).
% Here are various data types, expressed as multiple clauses of a function.
% When the function is called with a certain atom, it returns the example list.
data_types(atoms) ->
[
lower_cased_words_like_this,
'escaped values with single quotes',
'Even Works For Upper Case When Escaped'
];
data_types(lists) ->
[
[1,2,3],
[a,b,c],
"strings are technically lists of characters"
];
data_types(numbers) ->
[
1, % arbitrarily sized integer
2,
5.0, % floating point
3.14159,
16#deadbeef, % hexadecimal
8#077, % octal
2#001101, % binary
$E,$r,$l,$a,$n,$g,$!,$\n % Numeric values for the characters "Erlang!\n"
];
data_types(binaries) ->
[
<<1:4>>, % a 4-bit bit-string
<<"some string as a binary">>, % a full binary, created from this string
<<1,2,3>>, % a full binary, created from these integers
<<16#deadbeef:32/unsigned-integer-bigendian>>,
];
data_types(tuples) ->
[
{a,b,1,2}, % Some random stuff
{size,45,gigabytes}, % a lot of capacity
{size,36,'DD'}, % also a lot of capacity
#stuff{a=1,b=foo,c="bar"}, % records are just tuples in disguise
{stuff,1,foo,"bar"}, % the above record as a raw tuple
];
data_types(exotic) ->
[
fun (X,Y,Z) -> % an anonymous function
this_is_a_function
end,
fun lists:foreach/2, % an external function
self(), % returns a process ID
make_ref() % returns a reference
].
control_structures(A,B,C) ->
Check0 = if % note, these clauses are guards, not full expressions
A > 5 -> bigger_than_5;
A < 0 -> negative;
B > C -> stuff;
true -> default_value
end,
Check1 = case {check1,A,B+C} of % the extra atom helps locate match failures
{check1,1,2} -> stuff;
{check1,2,X} when X > 5 -> other_stuff;
{check1,3,Y} ->
case {subcheck,Y} of % the extra atom helps locate match failures
{subcheck,0} -> zero;
{subcheck,_} -> default_value
end;
_ -> default_value
end,
Check2 = try A / B of % Note, the case-like matching part is optional
1 -> one_times; % exceptions are not caught here, only in the expression
2 -> two_times;
3 -> three_times;
X when X < 0 -> fractional;
X when X > 3 -> a_bunch;
_ -> default_value
catch
error:bad_arith -> division_by_zero;
error:_ -> some_other_error
end,
ok.
% TODO: Pattern Matches
% TODO: Standard Behaviors
% TODO: Messaging and Receiving
% TODO: Tail-Recursion
% TODO: Macros
% TODO: List Comprehensions
