Bend/examples/radix_sort.bend
2024-05-25 19:03:13 +02:00

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type Map_:
Free
Used
Both {~a, ~b}
type Arr:
Null
Leaf {~a}
Node {~a, ~b}
def swap(s, a, b):
switch s:
case 0:
return Map_/Both{ a: a, b: b }
case _:
return Map_/Both{ a: b, b: a }
# Sort : Arr -> Arr
def sort(t):
return to_arr(0, to_map(t))
# ToMap : Arr -> Map
def to_map(t):
match t:
case Arr/Null:
return Map_/Free
case Arr/Leaf:
return radix(t.a)
case Arr/Node:
return merge(to_map(t.a), to_map(t.b))
# ToArr : U60 -> Map -> Arr
def to_arr(x, m):
match m:
case Map_/Free:
return Arr/Null
case Map_/Used:
return Arr/Leaf{ a: x }
case Map_/Both:
return Arr/Node{ a: to_arr(x * 2, m.a), b: to_arr(x * 2 + 1, m.b) }
# Merge : Map -> Map -> Map
def merge(a, b):
match a:
case Map_/Free:
return b
case Map_/Used:
return Map_/Used
case Map_/Both:
match b:
case Map_/Free:
return a
case Map_/Used:
return Map_/Used
case Map_/Both:
return Map_/Both{ a: merge(a.a, b.a), b: merge(a.b, b.b) }
# Radix : U60 -> Map
def radix(n):
r = Map_/Used
r = swap(n & 1, r, Map_/Free)
r = swap(n & 2, r, Map_/Free)
r = swap(n & 4, r, Map_/Free)
r = swap(n & 8, r, Map_/Free)
r = swap(n & 16, r, Map_/Free)
r = swap(n & 32, r, Map_/Free)
r = swap(n & 64, r, Map_/Free)
r = swap(n & 128, r, Map_/Free)
r = swap(n & 256, r, Map_/Free)
r = swap(n & 512, r, Map_/Free)
return radix2(n, r)
# At the moment, we need to manually break very large functions into smaller ones
# if we want to run this program on the GPU.
# In a future version of Bend, we will be able to do this automatically.
def radix2(n, r):
r = swap(n & 1024, r, Map_/Free)
r = swap(n & 2048, r, Map_/Free)
r = swap(n & 4096, r, Map_/Free)
r = swap(n & 8192, r, Map_/Free)
r = swap(n & 16384, r, Map_/Free)
r = swap(n & 32768, r, Map_/Free)
r = swap(n & 65536, r, Map_/Free)
r = swap(n & 131072, r, Map_/Free)
r = swap(n & 262144, r, Map_/Free)
r = swap(n & 524288, r, Map_/Free)
return radix3(n, r)
def radix3(n, r):
r = swap(n & 1048576, r, Map_/Free)
r = swap(n & 2097152, r, Map_/Free)
r = swap(n & 4194304, r, Map_/Free)
r = swap(n & 8388608, r, Map_/Free)
return r
def reverse(t):
match t:
case Arr/Null:
return Arr/Null
case Arr/Leaf:
return t
case Arr/Node:
return Arr/Node{ a: reverse(t.b), b: reverse(t.a) }
# Sum : Arr -> U60
def sum(t):
match t:
case Arr/Null:
return 0
case Arr/Leaf:
return t.a
case Arr/Node:
return sum(t.a) + sum(t.b)
# Gen : U60 -> Arr
def gen(n):
return gen_go(n, 0)
def gen_go(n, x):
switch n:
case 0:
return Arr/Leaf{ a: x }
case _:
a = x * 2
b = x * 2 + 1
return Arr/Node{ a: gen_go(n-1, a), b: gen_go(n-1, b) }
Main = (sum (sort(reverse(gen 4))))