summaryrefslogtreecommitdiffhomepage
path: root/julia.html.markdown
blob: 8245e6166c2a13e67cca4f9c2b3c6ab83873e50a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
---
language: julia
contributors:
    - ["Leah Hanson", "http://leahhanson.us"]
filename: learnjulia.jl
---

Julia is a new homoiconic functional language focused on technical computing.
While having the full power of homoiconic macros, first-class functions, and low-level control, Julia is as easy to learn and use as Python.

This is based on the current development version of Julia, as of October 18th, 2013.

```ruby

# Single line comments start with a hash.

####################################################
## 1. Primitive Datatypes and Operators
####################################################

# Everything in Julia is a expression.

# There are several basic types of numbers.
3 # => 3 (Int64)
3.2 # => 3.2 (Float64)
2 + 1im # => 2 + 1im (Complex{Int64})
2//3 # => 2//3 (Rational{Int64})

# All of the normal infix operators are available.
1 + 1 # => 2
8 - 1 # => 7
10 * 2 # => 20
35 / 5 # => 7.0
5 / 2 # => 2.5 # dividing an Int by an Int always results in a Float
div(5, 2) # => 2 # for a truncated result, use div
5 \ 35 # => 7.0
2 ^ 2 # => 4 # power, not bitwise xor
12 % 10 # => 2

# Enforce precedence with parentheses
(1 + 3) * 2 # => 8

# Bitwise Operators
~2 # => -3   # bitwise not
3 & 5 # => 1 # bitwise and
2 | 4 # => 6 # bitwise or
2 $ 4 # => 6 # bitwise xor
2 >>> 1 # => 1 # logical shift right
2 >> 1  # => 1 # arithmetic shift right
2 << 1  # => 4 # logical/arithmetic shift left

# You can use the bits function to see the binary representation of a number.
bits(12345)
# => "0000000000000000000000000000000000000000000000000011000000111001"
bits(12345.0)
# => "0100000011001000000111001000000000000000000000000000000000000000"

# Boolean values are primitives
true
false

# Boolean operators
!true # => false
!false # => true
1 == 1 # => true
2 == 1 # => false
1 != 1 # => false
2 != 1 # => true
1 < 10 # => true
1 > 10 # => false
2 <= 2 # => true
2 >= 2 # => true
# Comparisons can be chained
1 < 2 < 3 # => true
2 < 3 < 2 # => false

# Strings are created with "
"This is a string."

# Character literals are written with '
'a'

# A string can be indexed like an array of characters
"This is a string"[1] # => 'T' # Julia indexes from 1
# However, this is will not work well for UTF8 strings,
# so iterating over strings is recommended (map, for loops, etc).

# $ can be used for string interpolation:
"2 + 2 = $(2 + 2)" # => "2 + 2 = 4"
# You can put any Julia expression inside the parenthesis.

# Another way to format strings is the printf macro.
@printf "%d is less than %f" 4.5 5.3 # 5 is less than 5.300000

# Printing is easy
println("I'm Julia. Nice to meet you!")

####################################################
## 2. Variables and Collections
####################################################

# You don't declare variables before assigning to them.
some_var = 5 # => 5
some_var # => 5

# Accessing a previously unassigned variable is an error
try
    some_other_var # => ERROR: some_other_var not defined
catch e
    println(e)
end

# Variable names start with a letter.
# After that, you can use letters, digits, underscores, and exclamation points.
SomeOtherVar123! = 6 # => 6

# You can also use unicode characters
☃ = 8 # => 8
# These are especially handy for mathematical notation
2 * π # => 6.283185307179586

# A note on naming conventions in Julia:
#
# * Names of variables are in lower case, with word separation indicated by
#   underscores ('\_').
#
# * Names of Types begin with a capital letter and word separation is shown
#   with CamelCase instead of underscores.
#
# * Names of functions and macros are in lower case, without underscores.
#
# * Functions that modify their inputs have names that end in !. These
#   functions are sometimes called mutating functions or in-place functions.

# Arrays store a sequence of values indexed by integers 1 through n:
a = Int64[] # => 0-element Int64 Array

# 1-dimensional array literals can be written with comma-separated values.
b = [4, 5, 6] # => 3-element Int64 Array: [4, 5, 6]
b[1] # => 4
b[end] # => 6

# 2-dimentional arrays use space-separated values and semicolon-separated rows.
matrix = [1 2; 3 4] # => 2x2 Int64 Array: [1 2; 3 4]

# Add stuff to the end of a list with push! and append!
push!(a,1)     # => [1]
push!(a,2)     # => [1,2]
push!(a,4)     # => [1,2,4]
push!(a,3)     # => [1,2,4,3]
append!(a,b) # => [1,2,4,3,4,5,6]

# Remove from the end with pop
pop!(b)        # => 6 and b is now [4,5]

# Let's put it back
push!(b,6)   # b is now [4,5,6] again.

a[1] # => 1 # remember that Julia indexes from 1, not 0!

# end is a shorthand for the last index. It can be used in any
# indexing expression
a[end] # => 6

# we also have shift and unshift
shift!(a) # => 1 and a is now [2,4,3,4,5,6]
unshift!(a,7) # => [7,2,4,3,4,5,6]

# Function names that end in exclamations points indicate that they modify
# their argument.
arr = [5,4,6] # => 3-element Int64 Array: [5,4,6]
sort(arr) # => [4,5,6]; arr is still [5,4,6]
sort!(arr) # => [4,5,6]; arr is now [4,5,6]

# Looking out of bounds is a BoundsError
try
    a[0] # => ERROR: BoundsError() in getindex at array.jl:270
    a[end+1] # => ERROR: BoundsError() in getindex at array.jl:270
catch e
    println(e)
end

# Errors list the line and file they came from, even if it's in the standard
# library. If you built Julia from source, you can look in the folder base
# inside the julia folder to find these files.

# You can initialize arrays from ranges
a = [1:5] # => 5-element Int64 Array: [1,2,3,4,5]

# You can look at ranges with slice syntax.
a[1:3] # => [1, 2, 3]
a[2:] # => [2, 3, 4, 5]
a[2:end] # => [2, 3, 4, 5]

# Remove elements from an array by index with splice!
arr = [3,4,5]
splice!(arr,2) # => 4 ; arr is now [3,5]

# Concatenate lists with append!
b = [1,2,3]
append!(a,b) # Now a is [1, 2, 3, 4, 5, 1, 2, 3]

# Check for existence in a list with in
in(1, a) # => true

# Examine the length with length
length(a) # => 8

# Tuples are immutable.
tup = (1, 2, 3) # => (1,2,3) # an (Int64,Int64,Int64) tuple.
tup[1] # => 1
try:
    tup[1] = 3 # => ERROR: no method setindex!((Int64,Int64,Int64),Int64,Int64)
catch e
    println(e)
end

# Many list functions also work on tuples
length(tup) # => 3
tup[1:2] # => (1,2)
in(2, tup) # => true

# You can unpack tuples into variables
a, b, c = (1, 2, 3) # => (1,2,3)  # a is now 1, b is now 2 and c is now 3

# Tuples are created even if you leave out the parentheses
d, e, f = 4, 5, 6 # => (4,5,6)

# A 1-element tuple is distinct from the value it contains
(1,) == 1 # => false
(1) == 1 # => true

# Look how easy it is to swap two values
e, d = d, e  # => (5,4) # d is now 5 and e is now 4


# Dictionaries store mappings
empty_dict = Dict() # => Dict{Any,Any}()

# You can create a dictionary using a literal
filled_dict = ["one"=> 1, "two"=> 2, "three"=> 3]
# => Dict{ASCIIString,Int64}

# Look up values with []
filled_dict["one"] # => 1

# Get all keys
keys(filled_dict)
# => KeyIterator{Dict{ASCIIString,Int64}}(["three"=>3,"one"=>1,"two"=>2])
# Note - dictionary keys are not sorted or in the order you inserted them.

# Get all values
values(filled_dict)
# => ValueIterator{Dict{ASCIIString,Int64}}(["three"=>3,"one"=>1,"two"=>2])
# Note - Same as above regarding key ordering.

# Check for existence of keys in a dictionary with in, haskey
in(("one", 1), filled_dict) # => true
in(("two", 3), filled_dict) # => false
haskey(filled_dict, "one") # => true
haskey(filled_dict, 1) # => false

# Trying to look up a non-existant key will raise an error
try
    filled_dict["four"] # => ERROR: key not found: four in getindex at dict.jl:489
catch e
    println(e)
end

# Use the get method to avoid that error by providing a default value
# get(dictionary,key,default_value)
get(filled_dict,"one",4) # => 1
get(filled_dict,"four",4) # => 4

# Use Sets to represent collections of unordered, unique values
empty_set = Set() # => Set{Any}()
# Initialize a set with values
filled_set = Set(1,2,2,3,4) # => Set{Int64}(1,2,3,4)

# Add more values to a set
push!(filled_set,5) # => Set{Int64}(5,4,2,3,1)

# Check if the values are in the set
in(2, filled_set) # => true
in(10, filled_set) # => false

# There are functions for set intersection, union, and difference.
other_set = Set(3, 4, 5, 6) # => Set{Int64}(6,4,5,3)
intersect(filled_set, other_set) # => Set{Int64}(3,4,5)
union(filled_set, other_set) # => Set{Int64}(1,2,3,4,5,6)
setdiff(Set(1,2,3,4),Set(2,3,5)) # => Set{Int64}(1,4)


####################################################
## 3. Control Flow
####################################################

# Let's make a variable
some_var = 5

# Here is an if statement. Indentation is not meaningful in Julia.
if some_var > 10
    println("some_var is totally bigger than 10.")
elseif some_var < 10    # This elseif clause is optional.
    println("some_var is smaller than 10.")
else                    # The else clause is optional too.
    println("some_var is indeed 10.")
end
# => prints "some var is smaller than 10"


# For loops iterate over iterables.
# Iterable types include Range, Array, Set, Dict, and String.
for animal=["dog", "cat", "mouse"]
    println("$animal is a mammal")
    # You can use $ to interpolate variables or expression into strings
end
# prints:
#    dog is a mammal
#    cat is a mammal
#    mouse is a mammal

# You can use 'in' instead of '='.
for animal in ["dog", "cat", "mouse"]
    println("$animal is a mammal")
end
# prints:
#    dog is a mammal
#    cat is a mammal
#    mouse is a mammal

for a in ["dog"=>"mammal","cat"=>"mammal","mouse"=>"mammal"]
    println("$(a[1]) is a $(a[2])")
end
# prints:
#    dog is a mammal
#    cat is a mammal
#    mouse is a mammal

for (k,v) in ["dog"=>"mammal","cat"=>"mammal","mouse"=>"mammal"]
    println("$k is a $v")
end
# prints:
#    dog is a mammal
#    cat is a mammal
#    mouse is a mammal

# While loops loop while a condition is true
x = 0
while x < 4
    println(x)
    x += 1  # Shorthand for x = x + 1
end
# prints:
#   0
#   1
#   2
#   3

# Handle exceptions with a try/catch block
try
   error("help")
catch e
   println("caught it $e")
end
# => caught it ErrorException("help")


####################################################
## 4. Functions
####################################################

# The keyword 'function' creates new functions
#function name(arglist)
#  body...
#end
function add(x, y)
    println("x is $x and y is $y")

    # Functions return the value of their last statement
    x + y
end

add(5, 6) # => 11 after printing out "x is 5 and y is 6"

# You can define functions that take a variable number of
# positional arguments
function varargs(args...)
    return args
    # use the keyword return to return anywhere in the function
end
# => varargs (generic function with 1 method)

varargs(1,2,3) # => (1,2,3)

# The ... is called a splat.
# We just used it in a function definition.
# It can also be used in a fuction call,
# where it will splat an Array or Tuple's contents into the argument list.
Set([1,2,3])    # => Set{Array{Int64,1}}([1,2,3]) # produces a Set of Arrays
Set([1,2,3]...) # => Set{Int64}(1,2,3) # this is equivalent to Set(1,2,3)

x = (1,2,3)     # => (1,2,3)
Set(x)          # => Set{(Int64,Int64,Int64)}((1,2,3)) # a Set of Tuples
Set(x...)       # => Set{Int64}(2,3,1)


# You can define functions with optional positional arguments
function defaults(a,b,x=5,y=6)
    return "$a $b and $x $y"
end

defaults('h','g') # => "h g and 5 6"
defaults('h','g','j') # => "h g and j 6"
defaults('h','g','j','k') # => "h g and j k"
try
    defaults('h') # => ERROR: no method defaults(Char,)
    defaults() # => ERROR: no methods defaults()
catch e
    println(e)
end

# You can define functions that take keyword arguments
function keyword_args(;k1=4,name2="hello") # note the ;
    return ["k1"=>k1,"name2"=>name2]
end

keyword_args(name2="ness") # => ["name2"=>"ness","k1"=>4]
keyword_args(k1="mine") # => ["k1"=>"mine","name2"=>"hello"]
keyword_args() # => ["name2"=>"hello","k1"=>4]

# You can combine all kinds of arguments in the same function
function all_the_args(normal_arg, optional_positional_arg=2; keyword_arg="foo")
    println("normal arg: $normal_arg")
    println("optional arg: $optional_positional_arg")
    println("keyword arg: $keyword_arg")
end

all_the_args(1, 3, keyword_arg=4)
# prints:
#   normal arg: 1
#   optional arg: 3
#   keyword arg: 4

# Julia has first class functions
function create_adder(x)
    adder = function (y)
        return x + y
    end
    return adder
end

# This is "stabby lambda syntax" for creating anonymous functions
(x -> x > 2)(3) # => true

# This function is identical to create_adder implementation above.
function create_adder(x)
    y -> x + y
end

# You can also name the internal function, if you want
function create_adder(x)
    function adder(y)
        x + y
    end
    adder
end

add_10 = create_adder(10)
add_10(3) # => 13


# There are built-in higher order functions
map(add_10, [1,2,3]) # => [11, 12, 13]
filter(x -> x > 5, [3, 4, 5, 6, 7]) # => [6, 7]

# We can use list comprehensions for nicer maps
[add_10(i) for i=[1, 2, 3]] # => [11, 12, 13]
[add_10(i) for i in [1, 2, 3]] # => [11, 12, 13]

####################################################
## 5. Types
####################################################

# Julia has a type system.
# Every value has a type; variables do not have types themselves.
# You can use the `typeof` function to get the type of a value.
typeof(5) # => Int64

# Types are first-class values
typeof(Int64) # => DataType
typeof(DataType) # => DataType
# DataType is the type that represents types, including itself.

# Types are used for documentation, optimizations, and dispatch.
# They are not statically checked.

# Users can define types
# They are like records or structs in other languages.
# New types are defined used the `type` keyword.

# type Name
#   field::OptionalType
#   ...
# end
type Tiger
  taillength::Float64
  coatcolor # not including a type annotation is the same as `::Any`
end

# The default constructor's arguments are the properties
# of the type, in the order they are listed in the definition
tigger = Tiger(3.5,"orange") # => Tiger(3.5,"orange")

# The type doubles as the constructor function for values of that type
sherekhan = typeof(tigger)(5.6,"fire") # => Tiger(5.6,"fire")

# These struct-style types are called concrete types
# They can be instantiated, but cannot have subtypes.
# The other kind of types is abstract types.

# abstract Name
abstract Cat # just a name and point in the type hierarchy

# Abstract types cannot be instantiated, but can have subtypes.
# For example, Number is an abstract type
subtypes(Number) # => 6-element Array{Any,1}:
                 #     Complex{Float16}
                 #     Complex{Float32}
                 #     Complex{Float64}
                 #     Complex{T<:Real}
                 #     ImaginaryUnit
                 #     Real
subtypes(Cat) # => 0-element Array{Any,1}

# Every type has a super type; use the `super` function to get it.
typeof(5) # => Int64
super(Int64) # => Signed
super(Signed) # => Real
super(Real) # => Number
super(Number) # => Any
super(super(Signed)) # => Number
super(Any) # => Any
# All of these type, except for Int64, are abstract.

# <: is the subtyping operator
type Lion <: Cat # Lion is a subtype of Cat
  mane_color
  roar::String
end

# You can define more constructors for your type
# Just define a function of the same name as the type
# and call an existing constructor to get a value of the correct type
Lion(roar::String) = Lion("green",roar)
# This is an outer constructor because it's outside the type definition

type Panther <: Cat # Panther is also a subtype of Cat
  eye_color
  Panther() = new("green")
  # Panthers will only have this constructor, and no default constructor.
end
# Using inner constructors, like Panther does, gives you control
# over how values of the type can be created.
# When possible, you should use outer constructors rather than inner ones.

####################################################
## 6. Multiple-Dispatch
####################################################

# In Julia, all named functions are generic functions
# This means that they are built up from many small methods
# Each constructor for Lion is a method of the generic function Lion.

# For a non-constructor example, let's make a function meow:

# Definitions for Lion, Panther, Tiger
function meow(animal::Lion)
  animal.roar # access type properties using dot notation
end

function meow(animal::Panther)
  "grrr"
end

function meow(animal::Tiger)
  "rawwwr"
end

# Testing the meow function
meow(tigger) # => "rawwr"
meow(Lion("brown","ROAAR")) # => "ROAAR"
meow(Panther()) # => "grrr"

# Review the local type hierarchy
issubtype(Tiger,Cat) # => false
issubtype(Lion,Cat) # => true
issubtype(Panther,Cat) # => true

# Defining a function that takes Cats
function pet_cat(cat::Cat)
  println("The cat says $(meow(cat))")
end

pet_cat(Lion("42")) # => prints "The cat says 42"
try
    pet_cat(tigger) # => ERROR: no method pet_cat(Tiger,)
catch e
    println(e)
end

# In OO languages, single dispatch is common;
# this means that the method is picked based on the type of the first argument.
# In Julia, all of the argument types contribute to selecting the best method.

# Let's define a function with more arguments, so we can see the difference
function fight(t::Tiger,c::Cat)
  println("The $(t.coatcolor) tiger wins!")
end
# => fight (generic function with 1 method)

fight(tigger,Panther()) # => prints The orange tiger wins!
fight(tigger,Lion("ROAR")) # => prints The orange tiger wins!

# Let's change the behavior when the Cat is specifically a Lion
fight(t::Tiger,l::Lion) = println("The $(l.mane_color)-maned lion wins!")
# => fight (generic function with 2 methods)

fight(tigger,Panther()) # => prints The orange tiger wins!
fight(tigger,Lion("ROAR")) # => prints The green-maned lion wins!

# We don't need a Tiger in order to fight
fight(l::Lion,c::Cat) = println("The victorious cat says $(meow(c))")
# => fight (generic function with 3 methods)

fight(Lion("balooga!"),Panther()) # => prints The victorious cat says grrr
try
  fight(Panther(),Lion("RAWR")) # => ERROR: no method fight(Panther,Lion)
catch
end

# Also let the cat go first
fight(c::Cat,l::Lion) = println("The cat beats the Lion")
# => Warning: New definition
#    fight(Cat,Lion) at none:1
# is ambiguous with
#    fight(Lion,Cat) at none:2.
# Make sure
#    fight(Lion,Lion)
# is defined first.
#fight (generic function with 4 methods)

# This warning is because it's unclear which fight will be called in:
fight(Lion("RAR"),Lion("brown","rarrr")) # => prints The victorious cat says rarrr
# The result may be different in other versions of Julia

fight(l::Lion,l2::Lion) = println("The lions come to a tie")
fight(Lion("RAR"),Lion("brown","rarrr")) # => prints The lions come to a tie


# Under the hood
# You can take a look at the llvm  and the assembly code generated.

square_area(l) = l * l      # square_area (generic function with 1 method)

square_area(5) #25

# What happens when we feed square_area an integer?
code_native(square_area, (Int32,))  
	#	    .section    __TEXT,__text,regular,pure_instructions
	#	Filename: none
	#	Source line: 1              # Prologue
	#	    push    RBP
	#	    mov RBP, RSP
	#	Source line: 1
	#	    movsxd  RAX, EDI        # Fetch l from memory?
	#	    imul    RAX, RAX        # Square l and store the result in RAX
	#	    pop RBP                 # Restore old base pointer
	#	    ret                     # Result will still be in RAX

code_native(square_area, (Float32,))
	#	    .section    __TEXT,__text,regular,pure_instructions
	#	Filename: none
	#	Source line: 1
	#	    push    RBP
	#	    mov RBP, RSP
	#	Source line: 1
	#	    vmulss  XMM0, XMM0, XMM0  # Scalar single precision multiply (AVX)
	#	    pop RBP
	#	    ret

code_native(square_area, (Float64,))
	#	    .section    __TEXT,__text,regular,pure_instructions
	#	Filename: none
	#	Source line: 1
	#	    push    RBP
	#	    mov RBP, RSP
	#	Source line: 1
	#	    vmulsd  XMM0, XMM0, XMM0 # Scalar double precision multiply (AVX)
	#	    pop RBP
	#	    ret
	#	
# Note that julia will use floating point instructions if any of the
# arguements are floats.
# Let's calculate the area of a circle 
circle_area(r) = pi * r * r     # circle_area (generic function with 1 method)
circle_area(5)                  # 78.53981633974483

code_native(circle_area, (Int32,))
	#	    .section    __TEXT,__text,regular,pure_instructions
	#	Filename: none
	#	Source line: 1
	#	    push    RBP
	#	    mov RBP, RSP
	#	Source line: 1
	#	    vcvtsi2sd   XMM0, XMM0, EDI          # Load integer (r) from memory
	#	    movabs  RAX, 4593140240              # Load pi
	#	    vmulsd  XMM1, XMM0, QWORD PTR [RAX]  # pi * r
	#	    vmulsd  XMM0, XMM0, XMM1             # (pi * r) * r
	#	    pop RBP
	#	    ret
	#

code_native(circle_area, (Float64,))
	#	    .section    __TEXT,__text,regular,pure_instructions
	#	Filename: none
	#	Source line: 1
	#	    push    RBP
	#	    mov RBP, RSP
	#	    movabs  RAX, 4593140496
	#	Source line: 1
	#	    vmulsd  XMM1, XMM0, QWORD PTR [RAX]
	#	    vmulsd  XMM0, XMM1, XMM0
	#	    pop RBP
	#	    ret
	#	
```

## Further Reading

You can get a lot more detail from [The Julia Manual](http://docs.julialang.org/en/latest/manual/)

The best place to get help with Julia is the (very friendly) [mailing list](https://groups.google.com/forum/#!forum/julia-users).