Add type-stable first and last

Author: devmotion

src/array_partition.jl

@@ -195,6 +195,10 @@ Base.done(A::ArrayPartition,state) = done(Chain(A.x),state)
 Base.length(A::ArrayPartition) = sum((length(x) for x in A.x))
 Base.size(A::ArrayPartition) = (length(A),)
 
+# redefine first and last to avoid slow and not type-stable indexing
+Base.first(A::ArrayPartition) = first(first(A.x))
+Base.last(A::ArrayPartition) = last(last(A.x))
+
 ## display
 
 # restore the type rendering in Juno

test/partitions_test.jl

@@ -29,35 +29,40 @@ K = (*).(p,p2)
 x = ArrayPartition([1, 2], [3.0, 4.0])
 
 # similar partitions
-@inferred(similar(x))
-@inferred(similar(x, (2, 2)))
-@inferred(similar(x, Int))
-@inferred(similar(x, Int, (2, 2)))
-@inferred(similar(x, Int, Float64))
+@inferred similar(x)
+@inferred similar(x, (2, 2))
+@inferred similar(x, Int)
+@inferred similar(x, Int, (2, 2))
+@inferred similar(x, Int, Float64)
 
 # zeros
-@inferred(zeros(x))
-@inferred(zeros(x, (2,2)))
+@inferred zeros(x)
+@inferred zeros(x, (2,2))
+@inferred zero(x)
 
 # ones
-@inferred(ones(x))
-@inferred(ones(x, (2,2)))
+@inferred ones(x)
+@inferred ones(x, (2,2))
 
 # vector space calculations
-@inferred(x+5)
-@inferred(5+x)
-@inferred(x-5)
-@inferred(5-x)
-@inferred(x*5)
-@inferred(5*x)
-@inferred(x/5)
-@inferred(5\x)
-@inferred(x+x)
-@inferred(x-x)
+@inferred x+5
+@inferred 5+x
+@inferred x-5
+@inferred 5-x
+@inferred x*5
+@inferred 5*x
+@inferred x/5
+@inferred 5\x
+@inferred x+x
+@inferred x-x
+
+# indexing
+@inferred first(x)
+@inferred last(x)
 
 # broadcasting
 _scalar_op(y) = y + 1
 # Can't do `@inferred(_scalar_op.(x))` so we wrap that in a function:
 _broadcast_wrapper(y) = _scalar_op.(y)
 # Issue #8
-@inferred(_broadcast_wrapper(x))
+@inferred _broadcast_wrapper(x)