mirror of
https://github.com/adambard/learnxinyminutes-docs.git
synced 2025-08-27 08:37:36 +02:00
Merge pull request #3189 from visr/julia1
[julia/en] update to run on julia 1.0
This commit is contained in:
Adam Bard
GitHub
@@ -2,17 +2,17 @@
|
||||
language: Julia
|
||||
contributors:
|
||||
- ["Leah Hanson", "http://leahhanson.us"]
|
||||
- ["Pranit Bauva", "http://github.com/pranitbauva1997"]
|
||||
- ["Daniel YC Lin", "http://github.com/dlintw"]
|
||||
- ["Pranit Bauva", "https://github.com/pranitbauva1997"]
|
||||
- ["Daniel YC Lin", "https://github.com/dlintw"]
|
||||
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 Julia 0.6.4
|
||||
This is based on Julia 1.0.0
|
||||
|
||||
```ruby
|
||||
```julia
|
||||
|
||||
# Single line comments start with a hash (pound) symbol.
|
||||
#= Multiline comments can be written
|
||||
@@ -30,17 +30,17 @@ This is based on Julia 0.6.4
|
||||
3 # => 3 (Int64)
|
||||
3.2 # => 3.2 (Float64)
|
||||
2 + 1im # => 2 + 1im (Complex{Int64})
|
||||
2//3 # => 2//3 (Rational{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
|
||||
5 / 2 # => 2.5 # dividing integers always results in a Float64
|
||||
div(5, 2) # => 2 # for a truncated result, use div
|
||||
5 \ 35 # => 7.0
|
||||
2 ^ 2 # => 4 # power, not bitwise xor
|
||||
2^2 # => 4 # power, not bitwise xor
|
||||
12 % 10 # => 2
|
||||
|
||||
# Enforce precedence with parentheses
|
||||
@@ -55,10 +55,10 @@ xor(2, 4) # => 6 # bitwise xor
|
||||
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)
|
||||
# Use the bitstring function to see the binary representation of a number.
|
||||
bitstring(12345)
|
||||
# => "0000000000000000000000000000000000000000000000000011000000111001"
|
||||
bits(12345.0)
|
||||
bitstring(12345.0)
|
||||
# => "0100000011001000000111001000000000000000000000000000000000000000"
|
||||
|
||||
# Boolean values are primitives
|
||||
@@ -81,33 +81,23 @@ false
|
||||
2 < 3 < 2 # => false
|
||||
|
||||
# Strings are created with "
|
||||
try
|
||||
"This is a string."
|
||||
catch ; end
|
||||
|
||||
# Julia has several types of strings, including ASCIIString and UTF8String.
|
||||
# More on this in the Types section.
|
||||
|
||||
# Character literals are written with '
|
||||
try
|
||||
'a'
|
||||
catch ; end
|
||||
|
||||
# Some strings can be indexed like an array of characters
|
||||
try
|
||||
"This is a string"[1] # => 'T' # Julia indexes from 1
|
||||
catch ; end
|
||||
# However, this is will not work well for UTF8 strings,
|
||||
# so iterating over strings is recommended (map, for loops, etc).
|
||||
# Strings are UTF8 encoded. Only if they contain only ASCII characters can
|
||||
# they be safely indexed.
|
||||
ascii("This is a string")[1] # => 'T' # Julia indexes from 1
|
||||
# Otherwise, iterating over strings is recommended (map, for loops, etc).
|
||||
|
||||
# $ can be used for string interpolation:
|
||||
try
|
||||
"2 + 2 = $(2 + 2)" # => "2 + 2 = 4"
|
||||
catch ; end
|
||||
# You can put any Julia expression inside the parentheses.
|
||||
|
||||
# Another way to format strings is the printf macro.
|
||||
@printf "%d is less than %f" 4.5 5.3 # 4 is less than 5.300000
|
||||
# Another way to format strings is the printf macro from the stdlib Printf.
|
||||
using Printf
|
||||
@printf "%d is less than %f\n" 4.5 5.3 # => 5 is less than 5.300000
|
||||
|
||||
# Printing is easy
|
||||
println("I'm Julia. Nice to meet you!")
|
||||
@@ -115,7 +105,7 @@ println("I'm Julia. Nice to meet you!")
|
||||
# String can be compared lexicographically
|
||||
"good" > "bye" # => true
|
||||
"good" == "good" # => true
|
||||
"1 + 2 = 3" == "1 + 2 = $(1+2)" # => true
|
||||
"1 + 2 = 3" == "1 + 2 = $(1 + 2)" # => true
|
||||
|
||||
####################################################
|
||||
## 2. Variables and Collections
|
||||
@@ -127,7 +117,7 @@ some_var # => 5
|
||||
|
||||
# Accessing a previously unassigned variable is an error
|
||||
try
|
||||
some_other_var # => ERROR: some_other_var not defined
|
||||
some_other_var # => ERROR: UndefVarError: some_other_var not defined
|
||||
catch e
|
||||
println(e)
|
||||
end
|
||||
@@ -167,21 +157,21 @@ b[end] # => 6
|
||||
# 2-dimensional arrays use space-separated values and semicolon-separated rows.
|
||||
matrix = [1 2; 3 4] # => 2x2 Int64 Array: [1 2; 3 4]
|
||||
|
||||
# Arrays of a particular Type
|
||||
# Arrays of a particular type
|
||||
b = Int8[4, 5, 6] # => 3-element Int8 Array: [4, 5, 6]
|
||||
|
||||
# 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]
|
||||
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.
|
||||
push!(b, 6) # b is now [4,5,6] again.
|
||||
|
||||
a[1] # => 1 # remember that Julia indexes from 1, not 0!
|
||||
|
||||
@@ -189,9 +179,9 @@ a[1] # => 1 # remember that Julia indexes from 1, not 0!
|
||||
# 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]
|
||||
# we also have popfirst! and pushfirst!
|
||||
popfirst!(a) # => 1 and a is now [2,4,3,4,5,6]
|
||||
pushfirst!(a, 7) # => [7,2,4,3,4,5,6]
|
||||
|
||||
# Function names that end in exclamations points indicate that they modify
|
||||
# their argument.
|
||||
@@ -201,15 +191,17 @@ 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
|
||||
a[0]
|
||||
# => BoundsError: attempt to access 7-element Array{Int64,1} at index [0]
|
||||
a[end + 1]
|
||||
# => BoundsError: attempt to access 7-element Array{Int64,1} at index [8]
|
||||
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.
|
||||
# library. You can look in the folder share/julia 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]
|
||||
@@ -220,11 +212,11 @@ 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]
|
||||
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]
|
||||
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
|
||||
@@ -235,13 +227,13 @@ length(a) # => 8
|
||||
# Tuples are immutable.
|
||||
tup = (1, 2, 3) # => (1,2,3) # an (Int64,Int64,Int64) tuple.
|
||||
tup[1] # => 1
|
||||
try:
|
||||
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
|
||||
# Many array functions also work on tuples
|
||||
length(tup) # => 3
|
||||
tup[1:2] # => (1,2)
|
||||
in(2, tup) # => true
|
||||
@@ -264,20 +256,21 @@ e, d = d, e # => (5,4) # d is now 5 and e is now 4
|
||||
empty_dict = Dict() # => Dict{Any,Any}()
|
||||
|
||||
# You can create a dictionary using a literal
|
||||
filled_dict = Dict("one"=> 1, "two"=> 2, "three"=> 3)
|
||||
# => Dict{ASCIIString,Int64}
|
||||
filled_dict = Dict("one" => 1, "two" => 2, "three" => 3)
|
||||
# => Dict{String,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])
|
||||
# => Base.KeySet for a Dict{String,Int64} with 3 entries. Keys:
|
||||
# "two", "one", "three"
|
||||
# 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])
|
||||
# => Base.ValueIterator{Dict{String,Int64}} with 3 entries. Values: 2, 1, 3
|
||||
# Note - Same as above regarding key ordering.
|
||||
|
||||
# Check for existence of keys in a dictionary with in, haskey
|
||||
@@ -288,33 +281,33 @@ haskey(filled_dict, 1) # => false
|
||||
|
||||
# Trying to look up a non-existent key will raise an error
|
||||
try
|
||||
filled_dict["four"] # => ERROR: key not found: four in getindex at dict.jl:489
|
||||
filled_dict["four"] # => KeyError: key "four" not found
|
||||
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
|
||||
# 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)
|
||||
filled_set = Set([1, 2, 2, 3, 4]) # => Set([4, 2, 3, 1])
|
||||
|
||||
# Add more values to a set
|
||||
push!(filled_set,5) # => Set{Int64}(5,4,2,3,1)
|
||||
push!(filled_set, 5) # => Set([4, 2, 3, 5, 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)
|
||||
other_set = Set([3, 4, 5, 6]) # => Set([4, 3, 5, 6])
|
||||
intersect(filled_set, other_set) # => Set([4, 3, 5])
|
||||
union(filled_set, other_set) # => Set([4, 2, 3, 5, 6, 1])
|
||||
setdiff(Set([1,2,3,4]), Set([2,3,5])) # => Set([4, 1])
|
||||
|
||||
|
||||
####################################################
|
||||
@@ -337,7 +330,7 @@ end
|
||||
|
||||
# For loops iterate over iterables.
|
||||
# Iterable types include Range, Array, Set, Dict, and AbstractString.
|
||||
for animal=["dog", "cat", "mouse"]
|
||||
for animal = ["dog", "cat", "mouse"]
|
||||
println("$animal is a mammal")
|
||||
# You can use $ to interpolate variables or expression into strings
|
||||
end
|
||||
@@ -355,15 +348,16 @@ end
|
||||
# cat is a mammal
|
||||
# mouse is a mammal
|
||||
|
||||
for a in Dict("dog"=>"mammal","cat"=>"mammal","mouse"=>"mammal")
|
||||
println("$(a[1]) is a $(a[2])")
|
||||
for pair in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal")
|
||||
from, to = pair
|
||||
println("$from is a $to")
|
||||
end
|
||||
# prints:
|
||||
# dog is a mammal
|
||||
# cat is a mammal
|
||||
# mouse is a mammal
|
||||
|
||||
for (k,v) in Dict("dog"=>"mammal","cat"=>"mammal","mouse"=>"mammal")
|
||||
for (k, v) in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal")
|
||||
println("$k is a $v")
|
||||
end
|
||||
# prints:
|
||||
@@ -372,10 +366,11 @@ end
|
||||
# mouse is a mammal
|
||||
|
||||
# While loops loop while a condition is true
|
||||
x = 0
|
||||
while x < 4
|
||||
let x = 0
|
||||
while x < 4
|
||||
println(x)
|
||||
x += 1 # Shorthand for x = x + 1
|
||||
end
|
||||
end
|
||||
# prints:
|
||||
# 0
|
||||
@@ -425,7 +420,7 @@ function varargs(args...)
|
||||
end
|
||||
# => varargs (generic function with 1 method)
|
||||
|
||||
varargs(1,2,3) # => (1,2,3)
|
||||
varargs(1, 2, 3) # => (1,2,3)
|
||||
|
||||
# The ... is called a splat.
|
||||
# We just used it in a function definition.
|
||||
@@ -433,18 +428,18 @@ varargs(1,2,3) # => (1,2,3)
|
||||
# where it will splat an Array or Tuple's contents into the argument list.
|
||||
add([5,6]...) # this is equivalent to add(5,6)
|
||||
|
||||
x = (5,6) # => (5,6)
|
||||
x = (5, 6) # => (5,6)
|
||||
add(x...) # this is equivalent to add(5,6)
|
||||
|
||||
|
||||
# You can define functions with optional positional arguments
|
||||
function defaults(a,b,x=5,y=6)
|
||||
function defaults(a, b, x=5, y=6)
|
||||
return "$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"
|
||||
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()
|
||||
@@ -453,8 +448,8 @@ catch e
|
||||
end
|
||||
|
||||
# You can define functions that take keyword arguments
|
||||
function keyword_args(;k1=4,name2="hello") # note the ;
|
||||
return Dict("k1"=>k1,"name2"=>name2)
|
||||
function keyword_args(;k1=4, name2="hello") # note the ;
|
||||
return Dict("k1" => k1, "name2" => name2)
|
||||
end
|
||||
|
||||
keyword_args(name2="ness") # => ["name2"=>"ness","k1"=>4]
|
||||
@@ -507,7 +502,7 @@ 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
|
||||
[add_10(i) for i=[1, 2, 3]] # => [11, 12, 13]
|
||||
[add_10(i) for i = [1, 2, 3]] # => [11, 12, 13]
|
||||
[add_10(i) for i in [1, 2, 3]] # => [11, 12, 13]
|
||||
[x for x in [3, 4, 5, 6, 7] if x > 5] # => [6, 7]
|
||||
|
||||
@@ -530,23 +525,23 @@ typeof(DataType) # => DataType
|
||||
|
||||
# Users can define types
|
||||
# They are like records or structs in other languages.
|
||||
# New types are defined using the `type` keyword.
|
||||
# New types are defined using the `struct` keyword.
|
||||
|
||||
# type Name
|
||||
# struct Name
|
||||
# field::OptionalType
|
||||
# ...
|
||||
# end
|
||||
type Tiger
|
||||
struct 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")
|
||||
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")
|
||||
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.
|
||||
@@ -556,6 +551,7 @@ sherekhan = typeof(tigger)(5.6,"fire") # => Tiger(5.6,"fire")
|
||||
abstract type Cat end # just a name and point in the type hierarchy
|
||||
|
||||
# Abstract types cannot be instantiated, but can have subtypes.
|
||||
using InteractiveUtils # defines the subtype and supertype function
|
||||
# For example, Number is an abstract type
|
||||
subtypes(Number) # => 2-element Array{Any,1}:
|
||||
# Complex{T<:Real}
|
||||
@@ -563,13 +559,11 @@ subtypes(Number) # => 2-element Array{Any,1}:
|
||||
subtypes(Cat) # => 0-element Array{Any,1}
|
||||
|
||||
# AbstractString, as the name implies, is also an abstract type
|
||||
subtypes(AbstractString) # 6-element Array{Union{DataType, UnionAll},1}:
|
||||
# Base.SubstitutionString
|
||||
# Base.Test.GenericString
|
||||
# DirectIndexString
|
||||
# RevString
|
||||
subtypes(AbstractString) # 4-element Array{Any,1}:
|
||||
# String
|
||||
# SubString
|
||||
# SubstitutionString
|
||||
# Test.GenericString
|
||||
|
||||
# Every type has a super type; use the `supertype` function to get it.
|
||||
typeof(5) # => Int64
|
||||
@@ -584,10 +578,10 @@ supertype(Any) # => Any
|
||||
typeof("fire") # => String
|
||||
supertype(String) # => AbstractString
|
||||
# Likewise here with String
|
||||
supertype(DirectIndexString) # => AbstractString
|
||||
supertype(SubString) # => AbstractString
|
||||
|
||||
# <: is the subtyping operator
|
||||
type Lion <: Cat # Lion is a subtype of Cat
|
||||
struct Lion <: Cat # Lion is a subtype of Cat
|
||||
mane_color
|
||||
roar::AbstractString
|
||||
end
|
||||
@@ -595,10 +589,10 @@ 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::AbstractString) = Lion("green",roar)
|
||||
Lion(roar::AbstractString) = 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
|
||||
struct Panther <: Cat # Panther is also a subtype of Cat
|
||||
eye_color
|
||||
Panther() = new("green")
|
||||
# Panthers will only have this constructor, and no default constructor.
|
||||
@@ -632,13 +626,13 @@ end
|
||||
|
||||
# Testing the meow function
|
||||
meow(tigger) # => "rawwr"
|
||||
meow(Lion("brown","ROAAR")) # => "ROAAR"
|
||||
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
|
||||
Tiger <: Cat # => false
|
||||
Lion <: Cat # => true
|
||||
Panther <: Cat # => true
|
||||
|
||||
# Defining a function that takes Cats
|
||||
function pet_cat(cat::Cat)
|
||||
@@ -657,47 +651,50 @@ end
|
||||
# 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)
|
||||
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!
|
||||
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(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!
|
||||
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(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
|
||||
fight(Lion("balooga!"), Panther()) # => prints The victorious cat says grrr
|
||||
try
|
||||
fight(Panther(),Lion("RAWR"))
|
||||
fight(Panther(), Lion("RAWR"))
|
||||
catch e
|
||||
println(e)
|
||||
# => MethodError(fight, (Panther("green"), Lion("green", "RAWR")), 0x000000000000557b)
|
||||
# => MethodError(fight, (Panther("green"), Lion("green", "RAWR")),
|
||||
# 0x000000000000557b)
|
||||
end
|
||||
|
||||
# Also let the cat go first
|
||||
fight(c::Cat,l::Lion) = println("The cat beats the Lion")
|
||||
fight(c::Cat, l::Lion) = println("The cat beats the Lion")
|
||||
|
||||
# This warning is because it's unclear which fight will be called in:
|
||||
try
|
||||
fight(Lion("RAR"),Lion("brown","rarrr")) # => prints The victorious cat says rarrr
|
||||
fight(Lion("RAR"), Lion("brown", "rarrr"))
|
||||
# => prints The victorious cat says rarrr
|
||||
catch e
|
||||
println(e)
|
||||
# => MethodError(fight, (Lion("green", "RAR"), Lion("brown", "rarrr")), 0x000000000000557c)
|
||||
# => MethodError(fight, (Lion("green", "RAR"), Lion("brown", "rarrr")),
|
||||
# 0x000000000000557c)
|
||||
end
|
||||
# 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
|
||||
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
|
||||
@@ -705,7 +702,7 @@ fight(Lion("RAR"),Lion("brown","rarrr")) # => prints The lions come to a tie
|
||||
|
||||
square_area(l) = l * l # square_area (generic function with 1 method)
|
||||
|
||||
square_area(5) #25
|
||||
square_area(5) # => 25
|
||||
|
||||
# What happens when we feed square_area an integer?
|
||||
code_native(square_area, (Int32,))
|
||||
@@ -780,6 +777,6 @@ code_native(circle_area, (Float64,))
|
||||
|
||||
## Further Reading
|
||||
|
||||
You can get a lot more detail from [The Julia Manual](http://docs.julialang.org/en/latest/#Manual-1)
|
||||
You can get a lot more detail from the [Julia Documentation](https://docs.julialang.org/)
|
||||
|
||||
The best place to get help with Julia is the (very friendly) [Discourse forum](https://discourse.julialang.org/).
|
||||
|
||||
Reference in New Issue
Block a user