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-rw-r--r--julia.html.markdown56
1 files changed, 44 insertions, 12 deletions
diff --git a/julia.html.markdown b/julia.html.markdown
index 5ccd6484..ef3ea244 100644
--- a/julia.html.markdown
+++ b/julia.html.markdown
@@ -2,6 +2,7 @@
language: Julia
contributors:
- ["Leah Hanson", "http://leahhanson.us"]
+ - ["Pranit Bauva", "http://github.com/pranitbauva1997"]
filename: learnjulia.jl
---
@@ -14,7 +15,7 @@ This is based on Julia 0.3.
# Single line comments start with a hash (pound) symbol.
#= Multiline comments can be written
- by putting '#=' before the text and '=#'
+ by putting '#=' before the text and '=#'
after the text. They can also be nested.
=#
@@ -81,10 +82,13 @@ false
# Strings are created with "
"This is a string."
+# Julia has several types of strings, including ASCIIString and UTF8String.
+# More on this in the Types section.
+
# Character literals are written with '
'a'
-# A string can be indexed like an array of characters
+# Some strings 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).
@@ -99,6 +103,11 @@ false
# Printing is easy
println("I'm Julia. Nice to meet you!")
+# String can be compared lexicographically
+"good" > "bye" # => true
+"good" == "good" # => true
+"1 + 2 = 3" == "1 + 2 = $(1+2)" # => true
+
####################################################
## 2. Variables and Collections
####################################################
@@ -114,11 +123,11 @@ catch e
println(e)
end
-# Variable names start with a letter.
+# Variable names start with a letter or underscore.
# After that, you can use letters, digits, underscores, and exclamation points.
SomeOtherVar123! = 6 # => 6
-# You can also use unicode characters
+# You can also use certain unicode characters
☃ = 8 # => 8
# These are especially handy for mathematical notation
2 * π # => 6.283185307179586
@@ -314,7 +323,7 @@ end
# For loops iterate over iterables.
-# Iterable types include Range, Array, Set, Dict, and String.
+# Iterable types include Range, Array, Set, Dict, and AbstractString.
for animal=["dog", "cat", "mouse"]
println("$animal is a mammal")
# You can use $ to interpolate variables or expression into strings
@@ -387,6 +396,14 @@ end
add(5, 6) # => 11 after printing out "x is 5 and y is 6"
+# Compact assignment of functions
+f_add(x, y) = x + y # => "f (generic function with 1 method)"
+f_add(3, 4) # => 7
+
+# Function can also return multiple values as tuple
+f(x, y) = x + y, x - y
+f(3, 4) # => (7, -1)
+
# You can define functions that take a variable number of
# positional arguments
function varargs(args...)
@@ -537,6 +554,17 @@ subtypes(Number) # => 6-element Array{Any,1}:
# Real
subtypes(Cat) # => 0-element Array{Any,1}
+# AbstractString, as the name implies, is also an abstract type
+subtypes(AbstractString) # 8-element Array{Any,1}:
+ # Base.SubstitutionString{T<:AbstractString}
+ # DirectIndexString
+ # RepString
+ # RevString{T<:AbstractString}
+ # RopeString
+ # SubString{T<:AbstractString}
+ # UTF16String
+ # UTF8String
+
# Every type has a super type; use the `super` function to get it.
typeof(5) # => Int64
super(Int64) # => Signed
@@ -546,17 +574,21 @@ super(Number) # => Any
super(super(Signed)) # => Number
super(Any) # => Any
# All of these type, except for Int64, are abstract.
+typeof("fire") # => ASCIIString
+super(ASCIIString) # => DirectIndexString
+super(DirectIndexString) # => AbstractString
+# Likewise here with ASCIIString
# <: is the subtyping operator
type Lion <: Cat # Lion is a subtype of Cat
mane_color
- roar::String
+ roar::AbstractString
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)
+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
@@ -670,7 +702,7 @@ 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,))
+code_native(square_area, (Int32,))
# .section __TEXT,__text,regular,pure_instructions
# Filename: none
# Source line: 1 # Prologue
@@ -703,10 +735,10 @@ code_native(square_area, (Float64,))
# 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
+# arguments 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
@@ -737,7 +769,7 @@ code_native(circle_area, (Float64,))
# vmulsd XMM0, XMM1, XMM0
# pop RBP
# ret
- #
+ #
```
## Further Reading