diff options
Diffstat (limited to 'julia.html.markdown')
| -rw-r--r-- | julia.html.markdown | 65 |
1 files changed, 34 insertions, 31 deletions
diff --git a/julia.html.markdown b/julia.html.markdown index 5e9ef1b8..4d8eb497 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -11,7 +11,7 @@ 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 1.0.0 +This is based on Julia version 1.0.0. ```julia # Single line comments start with a hash (pound) symbol. @@ -83,7 +83,7 @@ false 1 > 10 # => false 2 <= 2 # => true 2 >= 2 # => true -# Comparisons can be chained +# Comparisons can be chained, like in Python but unlike many other languages 1 < 2 < 3 # => true 2 < 3 < 2 # => false @@ -93,28 +93,29 @@ false # Character literals are written with ' 'a' -# Strings are UTF8 encoded. Only if they contain only ASCII characters can -# they be safely indexed. -ascii("This is a string")[1] +# Strings are UTF8 encoded, so strings like "π" or "☃" are not directly equivalent +# to an array of single characters. +# Only if they contain only ASCII characters can they be safely indexed. +ascii("This is a string")[1] # => 'T' # => 'T': ASCII/Unicode U+0054 (category Lu: Letter, uppercase) -# Julia indexes from 1 +# Beware, Julia indexes everything from 1 (like MATLAB), not 0 (like most languages). # Otherwise, iterating over strings is recommended (map, for loops, etc). -# String can be compared lexicographically -"good" > "bye" # => true +# String can be compared lexicographically, in dictionnary order: +"good" > "bye" # => true "good" == "good" # => true "1 + 2 = 3" == "1 + 2 = $(1 + 2)" # => true -# $ can be used for string interpolation: +# $(..) can be used for string interpolation: "2 + 2 = $(2 + 2)" # => "2 + 2 = 4" # You can put any Julia expression inside the parentheses. # Printing is easy -println("I'm Julia. Nice to meet you!") # => I'm Julia. Nice to meet you! +println("I'm Julia. Nice to meet you!") # => I'm Julia. Nice to meet you! # 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 +using Printf # this is how you load (or import) a module +@printf "%d is less than %f\n" 4.5 5.3 # => 5 is less than 5.300000 #################################################### @@ -123,7 +124,7 @@ using Printf # You don't declare variables before assigning to them. someVar = 5 # => 5 -someVar # => 5 +someVar # => 5 # Accessing a previously unassigned variable is an error try @@ -137,9 +138,10 @@ end SomeOtherVar123! = 6 # => 6 # You can also use certain unicode characters +# here ☃ is a Unicode 'snowman' characters, see http://emojipedia.org/%E2%98%83%EF%B8%8F if it displays wrongly here ☃ = 8 # => 8 -# These are especially handy for mathematical notation -2 * π # => 6.283185307179586 +# These are especially handy for mathematical notation, like the constant π +2 * π # => 6.283185307179586 # A note on naming conventions in Julia: # @@ -171,7 +173,7 @@ matrix = [1 2; 3 4] # => 2×2 Array{Int64,2}: [1 2; 3 4] b = Int8[4, 5, 6] # => 3-element Array{Int8,1}: [4, 5, 6] # Add stuff to the end of a list with push! and append! -# By convention, the exclamation mark '!'' is appended to names of functions +# By convention, the exclamation mark '!' is appended to names of functions # that modify their arguments push!(a, 1) # => [1] push!(a, 2) # => [1,2] @@ -202,10 +204,10 @@ a # => [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 Array{Int64,1}: [5,4,6] -sort(arr) # => [4,5,6] -arr # => [5,4,6] -sort!(arr) # => [4,5,6] -arr # => [4,5,6] +sort(arr) # => [4,5,6] +arr # => [5,4,6] +sort!(arr) # => [4,5,6] +arr # => [4,5,6] # Looking out of bounds is a BoundsError try @@ -238,7 +240,7 @@ a = [1:5;] # => 5-element Array{Int64,1}: [1,2,3,4,5] a2 = [1:5] # => 1-element Array{UnitRange{Int64},1}: [1:5] # You can look at ranges with slice syntax. -a[1:3] # => [1, 2, 3] +a[1:3] # => [1, 2, 3] a[2:end] # => [2, 3, 4, 5] # Remove elements from an array by index with splice! @@ -276,15 +278,15 @@ in(2, tup) # => true # You can unpack tuples into variables a, b, c = (1, 2, 3) # => (1,2,3) -a # => 1 -b # => 2 -c # => 3 +a # => 1 +b # => 2 +c # => 3 # Tuples are created even if you leave out the parentheses d, e, f = 4, 5, 6 # => (4,5,6) -d # => 4 -e # => 5 -f # => 6 +d # => 4 +e # => 5 +f # => 6 # A 1-element tuple is distinct from the value it contains (1,) == 1 # => false @@ -292,8 +294,8 @@ f # => 6 # Look how easy it is to swap two values e, d = d, e # => (5,4) -d # => 5 -e # => 4 +d # => 5 +e # => 4 # Dictionaries store mappings emptyDict = Dict() # => Dict{Any,Any} with 0 entries @@ -375,7 +377,8 @@ end # 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 + # You can use $ to interpolate variables or expression into strings. + # In this special case, no need for parenthesis: $animal and $(animal) give the same end # => dog is a mammal # => cat is a mammal @@ -408,7 +411,7 @@ end let x = 0 while x < 4 println(x) - x += 1 # Shorthand for x = x + 1 + x += 1 # Shorthand for in place increment: x = x + 1 end end # => 0 |