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more comment spacing
This commit is contained in:
Martijn Visser
parent
10f50ca229
commit
c8ad0d0809
@ -33,27 +33,27 @@ This is based on Julia 1.0.0
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2 // 3 # => 2//3 (Rational{Int64})
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# All of the normal infix operators are available.
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1 + 1 # => 2
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8 - 1 # => 7
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10 * 2 # => 20
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35 / 5 # => 7.0
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5 / 2 # => 2.5 # dividing an Int by an Int always results in a Float
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div(5, 2) # => 2 # for a truncated result, use div
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5 \ 35 # => 7.0
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2^2 # => 4 # power, not bitwise xor
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12 % 10 # => 2
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1 + 1 # => 2
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8 - 1 # => 7
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10 * 2 # => 20
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35 / 5 # => 7.0
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5 / 2 # => 2.5 # dividing integers always results in a Float64
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div(5, 2) # => 2 # for a truncated result, use div
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5 \ 35 # => 7.0
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2^2 # => 4 # power, not bitwise xor
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12 % 10 # => 2
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# Enforce precedence with parentheses
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(1 + 3) * 2 # => 8
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# Bitwise Operators
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~2 # => -3 # bitwise not
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3 & 5 # => 1 # bitwise and
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2 | 4 # => 6 # bitwise or
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xor(2, 4) # => 6 # bitwise xor
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2 >>> 1 # => 1 # logical shift right
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2 >> 1 # => 1 # arithmetic shift right
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2 << 1 # => 4 # logical/arithmetic shift left
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~2 # => -3 # bitwise not
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3 & 5 # => 1 # bitwise and
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2 | 4 # => 6 # bitwise or
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xor(2, 4) # => 6 # bitwise xor
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2 >>> 1 # => 1 # logical shift right
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2 >> 1 # => 1 # arithmetic shift right
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2 << 1 # => 4 # logical/arithmetic shift left
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# You can use the bitstring function to see the binary representation of a number.
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bitstring(12345)
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@ -66,7 +66,7 @@ true
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false
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# Boolean operators
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!true # => false
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!true # => false
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!false # => true
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1 == 1 # => true
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2 == 1 # => false
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@ -172,17 +172,17 @@ matrix = [1 2; 3 4] # => 2x2 Int64 Array: [1 2; 3 4]
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b = Int8[4, 5, 6] # => 3-element Int8 Array: [4, 5, 6]
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# Add stuff to the end of a list with push! and append!
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push!(a, 1) # => [1]
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push!(a, 2) # => [1,2]
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push!(a, 4) # => [1,2,4]
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push!(a, 3) # => [1,2,4,3]
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append!(a, b) # => [1,2,4,3,4,5,6]
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push!(a, 1) # => [1]
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push!(a, 2) # => [1,2]
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push!(a, 4) # => [1,2,4]
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push!(a, 3) # => [1,2,4,3]
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append!(a, b) # => [1,2,4,3,4,5,6]
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# Remove from the end with pop
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pop!(b) # => 6 and b is now [4,5]
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pop!(b) # => 6 and b is now [4,5]
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# Let's put it back
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push!(b, 6) # b is now [4,5,6] again.
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push!(b, 6) # b is now [4,5,6] again.
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a[1] # => 1 # remember that Julia indexes from 1, not 0!
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@ -191,14 +191,14 @@ a[1] # => 1 # remember that Julia indexes from 1, not 0!
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a[end] # => 6
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# we also have popfirst! and pushfirst!
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popfirst!(a) # => 1 and a is now [2,4,3,4,5,6]
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pushfirst!(a, 7) # => [7,2,4,3,4,5,6]
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popfirst!(a) # => 1 and a is now [2,4,3,4,5,6]
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pushfirst!(a, 7) # => [7,2,4,3,4,5,6]
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# Function names that end in exclamations points indicate that they modify
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# their argument.
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arr = [5,4,6] # => 3-element Int64 Array: [5,4,6]
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sort(arr) # => [4,5,6]; arr is still [5,4,6]
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sort!(arr) # => [4,5,6]; arr is now [4,5,6]
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sort(arr) # => [4,5,6]; arr is still [5,4,6]
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sort!(arr) # => [4,5,6]; arr is now [4,5,6]
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# Looking out of bounds is a BoundsError
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try
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@ -221,20 +221,20 @@ a[2:end] # => [2, 3, 4, 5]
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# Remove elements from an array by index with splice!
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arr = [3,4,5]
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splice!(arr, 2) # => 4 ; arr is now [3,5]
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splice!(arr, 2) # => 4 ; arr is now [3,5]
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# Concatenate lists with append!
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b = [1,2,3]
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append!(a, b) # Now a is [1, 2, 3, 4, 5, 1, 2, 3]
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append!(a, b) # Now a is [1, 2, 3, 4, 5, 1, 2, 3]
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# Check for existence in a list with in
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in(1, a) # => true
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in(1, a) # => true
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# Examine the length with length
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length(a) # => 8
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length(a) # => 8
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# Tuples are immutable.
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tup = (1, 2, 3) # => (1,2,3) # an (Int64,Int64,Int64) tuple.
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tup = (1, 2, 3) # => (1,2,3) # an (Int64,Int64,Int64) tuple.
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tup[1] # => 1
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try
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tup[1] = 3 # => ERROR: no method setindex!((Int64,Int64,Int64),Int64,Int64)
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@ -243,12 +243,12 @@ catch e
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end
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# Many list functions also work on tuples
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length(tup) # => 3
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length(tup) # => 3
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tup[1:2] # => (1,2)
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in(2, tup) # => true
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in(2, tup) # => true
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# You can unpack tuples into variables
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a, b, c = (1, 2, 3) # => (1,2,3) # a is now 1, b is now 2 and c is now 3
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a, b, c = (1, 2, 3) # => (1,2,3) # a is now 1, b is now 2 and c is now 3
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# Tuples are created even if you leave out the parentheses
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d, e, f = 4, 5, 6 # => (4,5,6)
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@ -258,11 +258,11 @@ d, e, f = 4, 5, 6 # => (4,5,6)
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(1) == 1 # => true
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# Look how easy it is to swap two values
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e, d = d, e # => (5,4) # d is now 5 and e is now 4
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e, d = d, e # => (5,4) # d is now 5 and e is now 4
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# Dictionaries store mappings
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empty_dict = Dict() # => Dict{Any,Any}()
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empty_dict = Dict() # => Dict{Any,Any}()
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# You can create a dictionary using a literal
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filled_dict = Dict("one" => 1, "two" => 2, "three" => 3)
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@ -282,10 +282,10 @@ values(filled_dict)
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# Note - Same as above regarding key ordering.
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# Check for existence of keys in a dictionary with in, haskey
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in(("one" => 1), filled_dict) # => true
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in(("two" => 3), filled_dict) # => false
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haskey(filled_dict, "one") # => true
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haskey(filled_dict, 1) # => false
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in(("one" => 1), filled_dict) # => true
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in(("two" => 3), filled_dict) # => false
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haskey(filled_dict, "one") # => true
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haskey(filled_dict, 1) # => false
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# Trying to look up a non-existent key will raise an error
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try
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@ -296,26 +296,26 @@ end
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# Use the get method to avoid that error by providing a default value
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# get(dictionary,key,default_value)
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get(filled_dict, "one", 4) # => 1
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get(filled_dict, "four", 4) # => 4
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get(filled_dict, "one", 4) # => 1
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get(filled_dict, "four", 4) # => 4
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# Use Sets to represent collections of unordered, unique values
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empty_set = Set() # => Set{Any}()
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empty_set = Set() # => Set{Any}()
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# Initialize a set with values
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filled_set = Set([1,2,2,3,4]) # => Set{Int64}(1,2,3,4)
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filled_set = Set([1,2,2,3,4]) # => Set{Int64}(1,2,3,4)
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# Add more values to a set
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push!(filled_set, 5) # => Set{Int64}(5,4,2,3,1)
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push!(filled_set, 5) # => Set{Int64}(5,4,2,3,1)
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# Check if the values are in the set
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in(2, filled_set) # => true
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in(10, filled_set) # => false
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in(2, filled_set) # => true
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in(10, filled_set) # => false
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# There are functions for set intersection, union, and difference.
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other_set = Set([3, 4, 5, 6]) # => Set{Int64}(6,4,5,3)
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intersect(filled_set, other_set) # => Set{Int64}(3,4,5)
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union(filled_set, other_set) # => Set{Int64}(1,2,3,4,5,6)
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setdiff(Set([1,2,3,4]), Set([2,3,5])) # => Set{Int64}(1,4)
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other_set = Set([3, 4, 5, 6]) # => Set{Int64}(6,4,5,3)
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intersect(filled_set, other_set) # => Set{Int64}(3,4,5)
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union(filled_set, other_set) # => Set{Int64}(1,2,3,4,5,6)
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setdiff(Set([1,2,3,4]), Set([2,3,5])) # => Set{Int64}(1,4)
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####################################################
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@ -409,15 +409,15 @@ function add(x, y)
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x + y
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end
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add(5, 6) # => 11 after printing out "x is 5 and y is 6"
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add(5, 6) # => 11 after printing out "x is 5 and y is 6"
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# Compact assignment of functions
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f_add(x, y) = x + y # => "f (generic function with 1 method)"
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f_add(3, 4) # => 7
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f_add(3, 4) # => 7
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# Function can also return multiple values as tuple
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fn(x, y) = x + y, x - y
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fn(3, 4) # => (7, -1)
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fn(3, 4) # => (7, -1)
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# You can define functions that take a variable number of
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# positional arguments
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@ -427,16 +427,16 @@ function varargs(args...)
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end
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# => varargs (generic function with 1 method)
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varargs(1, 2, 3) # => (1,2,3)
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varargs(1, 2, 3) # => (1,2,3)
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# The ... is called a splat.
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# We just used it in a function definition.
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# It can also be used in a function call,
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# where it will splat an Array or Tuple's contents into the argument list.
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add([5,6]...) # this is equivalent to add(5,6)
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add([5,6]...) # this is equivalent to add(5,6)
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x = (5, 6) # => (5,6)
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add(x...) # this is equivalent to add(5,6)
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x = (5, 6) # => (5,6)
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add(x...) # this is equivalent to add(5,6)
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# You can define functions with optional positional arguments
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@ -444,24 +444,24 @@ function defaults(a, b, x=5, y=6)
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return "$a $b and $x $y"
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end
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defaults('h', 'g') # => "h g and 5 6"
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defaults('h', 'g', 'j') # => "h g and j 6"
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defaults('h', 'g', 'j', 'k') # => "h g and j k"
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defaults('h', 'g') # => "h g and 5 6"
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defaults('h', 'g', 'j') # => "h g and j 6"
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defaults('h', 'g', 'j', 'k') # => "h g and j k"
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try
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defaults('h') # => ERROR: no method defaults(Char,)
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defaults() # => ERROR: no methods defaults()
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defaults('h') # => ERROR: no method defaults(Char,)
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defaults() # => ERROR: no methods defaults()
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catch e
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println(e)
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end
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# You can define functions that take keyword arguments
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function keyword_args(;k1=4, name2="hello") # note the ;
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function keyword_args(;k1=4, name2="hello") # note the ;
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return Dict("k1" => k1, "name2" => name2)
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end
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keyword_args(name2="ness") # => ["name2"=>"ness","k1"=>4]
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keyword_args(k1="mine") # => ["k1"=>"mine","name2"=>"hello"]
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keyword_args() # => ["name2"=>"hello","k1"=>4]
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keyword_args(name2="ness") # => ["name2"=>"ness","k1"=>4]
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keyword_args(k1="mine") # => ["k1"=>"mine","name2"=>"hello"]
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keyword_args() # => ["name2"=>"hello","k1"=>4]
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# You can combine all kinds of arguments in the same function
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function all_the_args(normal_arg, optional_positional_arg=2; keyword_arg="foo")
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@ -485,7 +485,7 @@ function create_adder(x)
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end
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# This is "stabby lambda syntax" for creating anonymous functions
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(x -> x > 2)(3) # => true
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(x -> x > 2)(3) # => true
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# This function is identical to create_adder implementation above.
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function create_adder(x)
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@ -501,12 +501,12 @@ function create_adder(x)
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end
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add_10 = create_adder(10)
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add_10(3) # => 13
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add_10(3) # => 13
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# There are built-in higher order functions
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map(add_10, [1,2,3]) # => [11, 12, 13]
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filter(x -> x > 5, [3, 4, 5, 6, 7]) # => [6, 7]
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map(add_10, [1,2,3]) # => [11, 12, 13]
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filter(x -> x > 5, [3, 4, 5, 6, 7]) # => [6, 7]
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# We can use list comprehensions for nicer maps
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[add_10(i) for i = [1, 2, 3]] # => [11, 12, 13]
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@ -519,11 +519,11 @@ filter(x -> x > 5, [3, 4, 5, 6, 7]) # => [6, 7]
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# Julia has a type system.
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# Every value has a type; variables do not have types themselves.
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# You can use the `typeof` function to get the type of a value.
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typeof(5) # => Int64
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typeof(5) # => Int64
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# Types are first-class values
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typeof(Int64) # => DataType
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typeof(DataType) # => DataType
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typeof(Int64) # => DataType
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typeof(DataType) # => DataType
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# DataType is the type that represents types, including itself.
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# Types are used for documentation, optimizations, and dispatch.
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@ -544,10 +544,10 @@ end
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# The default constructor's arguments are the properties
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# of the type, in the order they are listed in the definition
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tigger = Tiger(3.5, "orange") # => Tiger(3.5,"orange")
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tigger = Tiger(3.5, "orange") # => Tiger(3.5,"orange")
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# The type doubles as the constructor function for values of that type
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sherekhan = typeof(tigger)(5.6, "fire") # => Tiger(5.6,"fire")
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sherekhan = typeof(tigger)(5.6, "fire") # => Tiger(5.6,"fire")
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# These struct-style types are called concrete types
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# They can be instantiated, but cannot have subtypes.
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@ -559,32 +559,32 @@ abstract type Cat end # just a name and point in the type hierarchy
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# Abstract types cannot be instantiated, but can have subtypes.
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using InteractiveUtils # defines the subtype and supertype function
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# For example, Number is an abstract type
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subtypes(Number) # => 2-element Array{Any,1}:
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subtypes(Number) # => 2-element Array{Any,1}:
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# Complex{T<:Real}
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# Real
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subtypes(Cat) # => 0-element Array{Any,1}
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subtypes(Cat) # => 0-element Array{Any,1}
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# AbstractString, as the name implies, is also an abstract type
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subtypes(AbstractString) # 4-element Array{Any,1}:
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subtypes(AbstractString) # 4-element Array{Any,1}:
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# String
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# SubString
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# SubstitutionString
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# Test.GenericString
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# Every type has a super type; use the `supertype` function to get it.
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typeof(5) # => Int64
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supertype(Int64) # => Signed
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supertype(Signed) # => Integer
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supertype(Integer) # => Real
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supertype(Real) # => Number
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supertype(Number) # => Any
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supertype(supertype(Signed)) # => Real
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supertype(Any) # => Any
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typeof(5) # => Int64
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supertype(Int64) # => Signed
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supertype(Signed) # => Integer
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supertype(Integer) # => Real
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supertype(Real) # => Number
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supertype(Number) # => Any
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supertype(supertype(Signed)) # => Real
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supertype(Any) # => Any
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# All of these type, except for Int64, are abstract.
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typeof("fire") # => String
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supertype(String) # => AbstractString
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typeof("fire") # => String
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supertype(String) # => AbstractString
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# Likewise here with String
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supertype(SubString) # => AbstractString
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supertype(SubString) # => AbstractString
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# <: is the subtyping operator
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struct Lion <: Cat # Lion is a subtype of Cat
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@ -631,9 +631,9 @@ function meow(animal::Tiger)
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end
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# Testing the meow function
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meow(tigger) # => "rawwr"
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meow(Lion("brown", "ROAAR")) # => "ROAAR"
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meow(Panther()) # => "grrr"
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meow(tigger) # => "rawwr"
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meow(Lion("brown", "ROAAR")) # => "ROAAR"
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meow(Panther()) # => "grrr"
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# Review the local type hierarchy
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Tiger <: Cat # => false
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@ -645,9 +645,9 @@ function pet_cat(cat::Cat)
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println("The cat says $(meow(cat))")
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end
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pet_cat(Lion("42")) # => prints "The cat says 42"
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pet_cat(Lion("42")) # => prints "The cat says 42"
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try
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pet_cat(tigger) # => ERROR: no method pet_cat(Tiger,)
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pet_cat(tigger) # => ERROR: no method pet_cat(Tiger,)
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catch e
|
||||
println(e)
|
||||
end
|
||||
@ -662,21 +662,21 @@ 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()) # => 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!
|
||||
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
|
||||
fight(Lion("balooga!"), Panther()) # => prints The victorious cat says grrr
|
||||
try
|
||||
fight(Panther(), Lion("RAWR"))
|
||||
catch e
|
||||
@ -689,7 +689,7 @@ 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)
|
||||
@ -697,7 +697,7 @@ 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(Lion("RAR"), Lion("brown", "rarrr")) # => prints The lions come to a tie
|
||||
|
||||
|
||||
# Under the hood
|
||||
@ -705,7 +705,7 @@ 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,))
|
||||
@ -746,7 +746,7 @@ code_native(square_area, (Float64,))
|
||||
# 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
|
||||
circle_area(5) # 78.53981633974483
|
||||
|
||||
code_native(circle_area, (Int32,))
|
||||
# .section __TEXT,__text,regular,pure_instructions
|
||||
|
||||
Loading…
Reference in New Issue
Block a user