From e1ab28f4fab138e7968041190a64ef0dc0a346a4 Mon Sep 17 00:00:00 2001 From: 0u0 Date: Wed, 29 Aug 2018 15:48:40 +0800 Subject: Keep a line 80 chars --- julia.html.markdown | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'julia.html.markdown') diff --git a/julia.html.markdown b/julia.html.markdown index 891a0a00..0b28d869 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -8,7 +8,8 @@ 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. +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 -- cgit v1.2.3 From 35215e4a2db7063f105eb30eb19cbf7b9d370cec Mon Sep 17 00:00:00 2001 From: 0u0 Date: Wed, 29 Aug 2018 15:55:04 +0800 Subject: Use more clearly example --- julia.html.markdown | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'julia.html.markdown') diff --git a/julia.html.markdown b/julia.html.markdown index 0b28d869..dfa3103c 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -28,17 +28,17 @@ This is based on Julia 1.0.0 # Everything in Julia is an 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}) +typeof(3) # => Int64 +typeof(3.2) # => Float64 +typeof(2 + 1im) # => Complex{Int64} +typeof(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 integers always results in a Float64 +10 / 2 # => 5.0 # 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 -- cgit v1.2.3 From 5691fb7a8d824a879a8d4391a93c50f27be1ec25 Mon Sep 17 00:00:00 2001 From: 0u0 Date: Fri, 31 Aug 2018 09:43:02 +0800 Subject: Update output for Julia 1.0 --- julia.html.markdown | 317 ++++++++++++++++++++++++++++++++-------------------- 1 file changed, 194 insertions(+), 123 deletions(-) (limited to 'julia.html.markdown') diff --git a/julia.html.markdown b/julia.html.markdown index dfa3103c..416f1a5a 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -89,7 +89,9 @@ false # 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 +ascii("This is a string")[1] +# => 'T': ASCII/Unicode U+0054 (category Lu: Letter, uppercase) +# Julia indexes from 1 # Otherwise, iterating over strings is recommended (map, for loops, etc). # $ can be used for string interpolation: @@ -101,7 +103,7 @@ 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!") +println("I'm Julia. Nice to meet you!") # => I'm Julia. Nice to meet you! # String can be compared lexicographically "good" > "bye" # => true @@ -147,19 +149,18 @@ SomeOtherVar123! = 6 # => 6 # 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 +a = Int64[] # => 0-element Array{Int64,1} # 1-dimensional array literals can be written with comma-separated values. -b = [4, 5, 6] # => 3-element Int64 Array: [4, 5, 6] -b = [4; 5; 6] # => 3-element Int64 Array: [4, 5, 6] -b[1] # => 4 +b = [4, 5, 6] # => 3-element Array{Int64,1}: [4, 5, 6] +b = [4; 5; 6] # => 3-element Array{Int64,1}: [4, 5, 6] 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] +matrix = [1 2; 3 4] # => 2×2 Array{Int64,2}: [1 2; 3 4] # Arrays of a particular type -b = Int8[4, 5, 6] # => 3-element Int8 Array: [4, 5, 6] +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! push!(a, 1) # => [1] @@ -186,16 +187,28 @@ pushfirst!(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] +arr = [5,4,6] # => 3-element Array{Int64,1}: [5,4,6] # Looking out of bounds is a BoundsError try - 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] + a[0] + # => ERROR: BoundsError: attempt to access 7-element Array{Int64,1} at + # index [0] + # => Stacktrace: + # => [1] getindex(::Array{Int64,1}, ::Int64) at .\array.jl:731 + # => [2] top-level scope at none:0 + # => [3] ... + # => in expression starting at ...\LearnJulia.jl:180 + a[end + 1] + # => ERROR: BoundsError: attempt to access 7-element Array{Int64,1} at + # index [8] + # => Stacktrace: + # => [1] getindex(::Array{Int64,1}, ::Int64) at .\array.jl:731 + # => [2] top-level scope at none:0 + # => [3] ... + # => in expression starting at ...\LearnJulia.jl:188 catch e println(e) end @@ -205,7 +218,8 @@ end # find these files. # You can initialize arrays from ranges -a = [1:5;] # => 5-element Int64 Array: [1,2,3,4,5] +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] @@ -229,7 +243,9 @@ length(a) # => 8 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) + tup[1] = 3 + # => ERROR: MethodError: no method matching + # setindex!(::Tuple{Int64,Int64,Int64}, ::Int64, ::Int64) catch e println(e) end @@ -254,11 +270,12 @@ e, d = d, e # => (5,4) # d is now 5 and e is now 4 # Dictionaries store mappings -empty_dict = Dict() # => Dict{Any,Any}() +empty_dict = Dict() # => Dict{Any,Any} with 0 entries # You can create a dictionary using a literal filled_dict = Dict("one" => 1, "two" => 2, "three" => 3) -# => Dict{String,Int64} +# => Dict{String,Int64} with 3 entries: +# => "two" => 2, "one" => 1, "three" => 3 # Look up values with [] filled_dict["one"] # => 1 @@ -266,12 +283,13 @@ filled_dict["one"] # => 1 # Get all keys keys(filled_dict) # => Base.KeySet for a Dict{String,Int64} with 3 entries. Keys: -# "two", "one", "three" +# => "two", "one", "three" # Note - dictionary keys are not sorted or in the order you inserted them. # Get all values values(filled_dict) -# => Base.ValueIterator{Dict{String,Int64}} with 3 entries. Values: 2, 1, 3 +# => Base.ValueIterator for a 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 @@ -282,7 +300,7 @@ haskey(filled_dict, 1) # => false # Trying to look up a non-existent key will raise an error try - filled_dict["four"] # => KeyError: key "four" not found + filled_dict["four"] # => ERROR: KeyError: key "four" not found catch e println(e) end @@ -293,7 +311,7 @@ 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}() +empty_set = Set() # => Set(Any[]) # Initialize a set with values filled_set = Set([1, 2, 2, 3, 4]) # => Set([4, 2, 3, 1]) @@ -353,18 +371,16 @@ for pair in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal") from, to = pair println("$from is a $to") end -# prints: -# dog is a mammal -# cat is a mammal -# mouse is a mammal +# => mouse is a mammal +# => cat is a mammal +# => dog is a mammal for (k, v) in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal") println("$k is a $v") end -# prints: -# dog is a mammal -# cat is a mammal -# mouse is a mammal +# => mouse is a mammal +# => cat is a mammal +# => dog is a mammal # While loops loop while a condition is true let x = 0 @@ -406,11 +422,11 @@ end add(5, 6) # => 11 after printing out "x is 5 and y is 6" # Compact assignment of functions -f_add(x, y) = x + y # => "f (generic function with 1 method)" +f_add(x, y) = x + y # => f_add (generic function with 1 method) f_add(3, 4) # => 7 # Function can also return multiple values as tuple -fn(x, y) = x + y, x - y +fn(x, y) = x + y, x - y # => fn (generic function with 1 method) fn(3, 4) # => (7, -1) # You can define functions that take a variable number of @@ -437,13 +453,14 @@ add(x...) # this is equivalent to add(5,6) function defaults(a, b, x=5, y=6) return "$a $b and $x $y" end +# => defaults (generic function with 3 methods) 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() + defaults('h') # => ERROR: MethodError: no method matching defaults(::Char) + defaults() # => ERROR: MethodError: no method matching defaults() catch e println(e) end @@ -452,10 +469,11 @@ end function keyword_args(;k1=4, name2="hello") # note the ; return Dict("k1" => k1, "name2" => name2) end +# => keyword_args (generic function with 1 method) -keyword_args(name2="ness") # => ["name2"=>"ness","k1"=>4] -keyword_args(k1="mine") # => ["k1"=>"mine","name2"=>"hello"] -keyword_args() # => ["name2"=>"hello","k1"=>4] +keyword_args(name2="ness") # => ["name2"=>"ness", "k1"=>4] +keyword_args(k1="mine") # => ["name2"=>"hello", "k1"=>"mine"] +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") @@ -463,6 +481,7 @@ function all_the_args(normal_arg, optional_positional_arg=2; keyword_arg="foo") println("optional arg: $optional_positional_arg") println("keyword arg: $keyword_arg") end +# => all_the_args (generic function with 2 methods) all_the_args(1, 3, keyword_arg=4) # prints: @@ -477,6 +496,7 @@ function create_adder(x) end return adder end +# => create_adder (generic function with 1 method) # This is "stabby lambda syntax" for creating anonymous functions (x -> x > 2)(3) # => true @@ -485,6 +505,7 @@ end function create_adder(x) y -> x + y end +# => create_adder (generic function with 1 method) # You can also name the internal function, if you want function create_adder(x) @@ -493,9 +514,11 @@ function create_adder(x) end adder end +# => create_adder (generic function with 1 method) -add_10 = create_adder(10) -add_10(3) # => 13 +add_10 = create_adder(10) # => (::getfield(Main, Symbol("#adder#11")){Int64}) + # (generic function with 1 method) +add_10(3) # => 13 # There are built-in higher order functions @@ -555,16 +578,16 @@ abstract type Cat end # just a name and point in the type hierarchy 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} - # Real + # => Complex + # => Real subtypes(Cat) # => 0-element Array{Any,1} # AbstractString, as the name implies, is also an abstract type -subtypes(AbstractString) # 4-element Array{Any,1}: - # String - # SubString - # SubstitutionString - # Test.GenericString +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 @@ -626,7 +649,7 @@ function meow(animal::Tiger) end # Testing the meow function -meow(tigger) # => "rawwr" +meow(tigger) # => "rawwwr" meow(Lion("brown", "ROAAR")) # => "ROAAR" meow(Panther()) # => "grrr" @@ -639,10 +662,11 @@ Panther <: Cat # => true function pet_cat(cat::Cat) println("The cat says $(meow(cat))") end +# => pet_cat (generic function with 1 method) -pet_cat(Lion("42")) # => prints "The cat says 42" +pet_cat(Lion("42")) # => The cat says 42 try - pet_cat(tigger) # => ERROR: no method pet_cat(Tiger,) + pet_cat(tigger) # => ERROR: MethodError: no method matching pet_cat(::Tiger) catch e println(e) end @@ -657,45 +681,54 @@ function fight(t::Tiger, c::Cat) 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()) # => The orange tiger wins! +fight(tigger, Lion("ROAR")) # => 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! +fight(tigger, Panther()) # => The orange tiger wins! +fight(tigger, Lion("ROAR")) # => 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 +fight(Lion("balooga!"), Panther()) # => The victorious cat says grrr try - fight(Panther(), Lion("RAWR")) + fight(Panther(), Lion("RAWR")) + # => ERROR: MethodError: no method matching fight(::Panther, ::Lion) + # => Closest candidates are: + # => fight(::Tiger, ::Lion) at ... + # => fight(::Tiger, ::Cat) at ... + # => fight(::Lion, ::Cat) at ... + # => ... catch e println(e) - # => 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 (generic function with 4 methods) # 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 + # => ERROR: MethodError: fight(::Lion, ::Lion) is ambiguous. Candidates: + # => fight(c::Cat, l::Lion) in Main at ... + # => fight(l::Lion, c::Cat) in Main at ... + # => Possible fix, define + # => fight(::Lion, ::Lion) + # => ... catch e println(e) - # => 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 (generic function with 5 methods) +fight(Lion("RAR"), Lion("brown", "rarrr")) # => The lions come to a tie # Under the hood @@ -706,74 +739,112 @@ 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 - # +code_native(square_area, (Int32,), syntax = :intel) + # .text + # ; Function square_area { + # ; Location: REPL[116]:1 # Prologue + # push rbp + # mov rbp, rsp + # ; Function *; { + # ; Location: int.jl:54 + # imul ecx, ecx # Square l and store the result in ECX + # ;} + # mov eax, ecx + # pop rbp # Restore old base pointer + # ret # Result will still be in EAX + # nop dword ptr [rax + rax] + # ;} + +code_native(square_area, (Float32,), syntax = :intel) + # .text + # ; Function square_area { + # ; Location: REPL[116]:1 + # push rbp + # mov rbp, rsp + # ; Function *; { + # ; Location: float.jl:398 + # vmulss xmm0, xmm0, xmm0 # Scalar single precision multiply (AVX) + # ;} + # pop rbp + # ret + # nop word ptr [rax + rax] + # ;} + +code_native(square_area, (Float64,), syntax = :intel) + # .text + # ; Function square_area { + # ; Location: REPL[116]:1 + # push rbp + # mov rbp, rsp + # ; Function *; { + # ; Location: float.jl:399 + # vmulsd xmm0, xmm0, xmm0 # Scalar double precision multiply (AVX) + # ;} + # pop rbp + # ret + # nop word ptr [rax + rax] + # ;} + # Note that julia will use floating point instructions if any of the # 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 -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 - # +code_native(circle_area, (Int32,), syntax = :intel) + # .text + # ; Function circle_area { + # ; Location: REPL[121]:1 + # push rbp + # mov rbp, rsp + # ; Function *; { + # ; Location: operators.jl:502 + # ; Function *; { + # ; Location: promotion.jl:314 + # ; Function promote; { + # ; Location: promotion.jl:284 + # ; Function _promote; { + # ; Location: promotion.jl:261 + # ; Function convert; { + # ; Location: number.jl:7 + # ; Function Type; { + # ; Location: float.jl:60 + # vcvtsi2sd xmm0, xmm0, ecx # Load integer (r) from memory + # movabs rax, 497710928 # Load pi + # ;}}}}} + # ; Function *; { + # ; Location: float.jl:399 + # vmulsd xmm1, xmm0, qword ptr [rax] # pi * r + # vmulsd xmm0, xmm1, xmm0 # (pi * r) * r + # ;}} + # pop rbp + # ret + # nop dword ptr [rax] + # ;} + +code_native(circle_area, (Float64,), syntax = :intel) + # .text + # ; Function circle_area { + # ; Location: REPL[121]:1 + # push rbp + # mov rbp, rsp + # movabs rax, 497711048 + # ; Function *; { + # ; Location: operators.jl:502 + # ; Function *; { + # ; Location: promotion.jl:314 + # ; Function *; { + # ; Location: float.jl:399 + # vmulsd xmm1, xmm0, qword ptr [rax] + # ;}}} + # ; Function *; { + # ; Location: float.jl:399 + # vmulsd xmm0, xmm1, xmm0 + # ;} + # pop rbp + # ret + # nop dword ptr [rax + rax] + # ;} ``` ## Further Reading -- cgit v1.2.3 From 4fcac31e9cfe169f006244dbdb01d0d16fa696e5 Mon Sep 17 00:00:00 2001 From: 0u0 Date: Fri, 31 Aug 2018 09:45:50 +0800 Subject: ry to use as few words as possible --- julia.html.markdown | 48 +++++++++++++++++++++++++++++++++--------------- 1 file changed, 33 insertions(+), 15 deletions(-) (limited to 'julia.html.markdown') diff --git a/julia.html.markdown b/julia.html.markdown index 416f1a5a..54860fca 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -170,10 +170,12 @@ 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] +pop!(b) # => 6 +b # => [4,5] # Let's put it back -push!(b, 6) # b is now [4,5,6] again. +push!(b, 6) # => [4,5,6] +b # => [4,5,6] a[1] # => 1 # remember that Julia indexes from 1, not 0! @@ -182,14 +184,18 @@ a[1] # => 1 # remember that Julia indexes from 1, not 0! a[end] # => 6 # we also have popfirst! and pushfirst! -popfirst!(a) # => 1 and a is now [2,4,3,4,5,6] +popfirst!(a) # => 1 +a # => [2,4,3,4,5,6] pushfirst!(a, 7) # => [7,2,4,3,4,5,6] +a # => [7,2,4,3,4,5,6] # Function names that end in exclamations points indicate that they modify # their argument. -sort(arr) # => [4,5,6]; arr is still [5,4,6] -sort!(arr) # => [4,5,6]; arr is now [4,5,6] 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] # Looking out of bounds is a BoundsError try @@ -227,11 +233,13 @@ 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 # => [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) # => [1, 2, 3, 4, 5, 1, 2, 3] +a # => [1, 2, 3, 4, 5, 1, 2, 3] # Check for existence in a list with in in(1, a) # => true @@ -240,8 +248,9 @@ in(1, a) # => true length(a) # => 8 # Tuples are immutable. -tup = (1, 2, 3) # => (1,2,3) # an (Int64,Int64,Int64) tuple. -tup[1] # => 1 +tup = (1, 2, 3) # => (1,2,3) +typeof(tup) # => Tuple{Int64,Int64,Int64} +tup[1] # => 1 try tup[1] = 3 # => ERROR: MethodError: no method matching @@ -251,23 +260,30 @@ catch e end # Many array functions also work on tuples -length(tup) # => 3 -tup[1:2] # => (1,2) +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 +a, b, c = (1, 2, 3) # => (1,2,3) +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 # 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 - +e, d = d, e # => (5,4) +d # => 5 +e # => 4 # Dictionaries store mappings empty_dict = Dict() # => Dict{Any,Any} with 0 entries @@ -419,7 +435,9 @@ function add(x, y) x + y end -add(5, 6) # => 11 after printing out "x is 5 and y is 6" +add(5, 6) +# => x is 5 and y is 6 +# => 11 # Compact assignment of functions f_add(x, y) = x + y # => f_add (generic function with 1 method) -- cgit v1.2.3 From 749e81ace2cf75710926cc0e9e35a8a675545648 Mon Sep 17 00:00:00 2001 From: 0u0 Date: Fri, 31 Aug 2018 09:46:52 +0800 Subject: Uniform output format --- julia.html.markdown | 30 +++++++++++++----------------- 1 file changed, 13 insertions(+), 17 deletions(-) (limited to 'julia.html.markdown') diff --git a/julia.html.markdown b/julia.html.markdown index 54860fca..fa614992 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -369,19 +369,17 @@ 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 +# => 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 +# => dog is a mammal +# => cat is a mammal +# => mouse is a mammal for pair in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal") from, to = pair @@ -405,11 +403,10 @@ let x = 0 x += 1 # Shorthand for x = x + 1 end end -# prints: -# 0 -# 1 -# 2 -# 3 +# => 0 +# => 1 +# => 2 +# => 3 # Handle exceptions with a try/catch block try @@ -502,10 +499,9 @@ end # => all_the_args (generic function with 2 methods) all_the_args(1, 3, keyword_arg=4) -# prints: -# normal arg: 1 -# optional arg: 3 -# keyword arg: 4 +# => normal arg: 1 +# => optional arg: 3 +# => keyword arg: 4 # Julia has first class functions function create_adder(x) -- cgit v1.2.3 From e96bfe490e2df68075e277cb18bdf58f90af2c0a Mon Sep 17 00:00:00 2001 From: 0u0 Date: Fri, 31 Aug 2018 09:47:30 +0800 Subject: Adjust for alignment --- julia.html.markdown | 51 +++++++++++++++++++++++++-------------------------- 1 file changed, 25 insertions(+), 26 deletions(-) (limited to 'julia.html.markdown') diff --git a/julia.html.markdown b/julia.html.markdown index fa614992..eadf6415 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -154,6 +154,7 @@ a = Int64[] # => 0-element Array{Int64,1} # 1-dimensional array literals can be written with comma-separated values. b = [4, 5, 6] # => 3-element Array{Int64,1}: [4, 5, 6] b = [4; 5; 6] # => 3-element Array{Int64,1}: [4, 5, 6] +b[1] # => 4 b[end] # => 6 # 2-dimensional arrays use space-separated values and semicolon-separated rows. @@ -277,7 +278,7 @@ e # => 5 f # => 6 # A 1-element tuple is distinct from the value it contains -(1,) == 1 # => false +(1,) == 1 # => false (1) == 1 # => true # Look how easy it is to swap two values @@ -335,15 +336,14 @@ filled_set = Set([1, 2, 2, 3, 4]) # => Set([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(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([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]) - +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]) #################################################### ## 3. Control Flow @@ -416,15 +416,14 @@ catch e end # => caught it ErrorException("help") - #################################################### ## 4. Functions #################################################### # The keyword 'function' creates new functions -#function name(arglist) -# body... -#end +# function name(arglist) +# body... +# end function add(x, y) println("x is $x and y is $y") @@ -540,8 +539,8 @@ 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 in [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] #################################################### @@ -554,7 +553,7 @@ filter(x -> x > 5, [3, 4, 5, 6, 7]) # => [6, 7] typeof(5) # => Int64 # Types are first-class values -typeof(Int64) # => DataType +typeof(Int64) # => DataType typeof(DataType) # => DataType # DataType is the type that represents types, including itself. @@ -604,17 +603,17 @@ subtypes(AbstractString) # => 4-element Array{Any,1}: # => Test.GenericString # Every type has a super type; use the `supertype` function to get it. -typeof(5) # => Int64 -supertype(Int64) # => Signed -supertype(Signed) # => Integer +typeof(5) # => Int64 +supertype(Int64) # => Signed +supertype(Signed) # => Integer supertype(Integer) # => Real -supertype(Real) # => Number -supertype(Number) # => Any +supertype(Real) # => Number +supertype(Number) # => Any supertype(supertype(Signed)) # => Real -supertype(Any) # => Any +supertype(Any) # => Any # All of these type, except for Int64, are abstract. -typeof("fire") # => String -supertype(String) # => AbstractString +typeof("fire") # => String +supertype(String) # => AbstractString # Likewise here with String supertype(SubString) # => AbstractString @@ -665,12 +664,12 @@ end # Testing the meow function meow(tigger) # => "rawwwr" meow(Lion("brown", "ROAAR")) # => "ROAAR" -meow(Panther()) # => "grrr" +meow(Panther()) # => "grrr" # Review the local type hierarchy -Tiger <: Cat # => false -Lion <: Cat # => true -Panther <: Cat # => true +Tiger <: Cat # => false +Lion <: Cat # => true +Panther <: Cat # => true # Defining a function that takes Cats function pet_cat(cat::Cat) -- cgit v1.2.3 From b0bbe39b46a1825563c903c0e9c25eed3c63293b Mon Sep 17 00:00:00 2001 From: 0u0 Date: Fri, 31 Aug 2018 09:50:30 +0800 Subject: remove useless Blank Lines --- julia.html.markdown | 2 -- 1 file changed, 2 deletions(-) (limited to 'julia.html.markdown') diff --git a/julia.html.markdown b/julia.html.markdown index eadf6415..3ef3148a 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -14,7 +14,6 @@ and low-level control, Julia is as easy to learn and use as Python. This is based on Julia 1.0.0 ```julia - # Single line comments start with a hash (pound) symbol. #= Multiline comments can be written by putting '#=' before the text and '=#' @@ -362,7 +361,6 @@ else # The else clause is optional too. end # => prints "some var is smaller than 10" - # For loops iterate over iterables. # Iterable types include Range, Array, Set, Dict, and AbstractString. for animal = ["dog", "cat", "mouse"] -- cgit v1.2.3 From 2a7bf762c65a50a609cc65c275267203309f97be Mon Sep 17 00:00:00 2001 From: 0u0 Date: Fri, 31 Aug 2018 11:24:57 +0800 Subject: Remove useless lib In fact, if you donot import InteractiveUtils, you still can use the subtype and supertype function --- julia.html.markdown | 1 - 1 file changed, 1 deletion(-) (limited to 'julia.html.markdown') diff --git a/julia.html.markdown b/julia.html.markdown index 3ef3148a..15c09da4 100644 --- a/julia.html.markdown +++ b/julia.html.markdown @@ -586,7 +586,6 @@ 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 -- cgit v1.2.3