Universal Lambda Machine: Difference between revisions

=={{header|Python}}==

<syntaxhighlight lang="python">#!/usr/local/bin/python3

import os,sys

def bit2lam(bit) :

return lambda x0: lambda x1: x1 if bit else x0

def byte2lam(bits,n) :

if (n==0) :

return lambda _:lambda y: y

return lambda z: z (bit2lam((bits>>(n-1))&1)) (byte2lam(bits,n-1))

def input(n) : # input from n'th character onward

if n >= len(inp) :

c = os.read(0,1)

inp.append((lambda _: lambda y: y) if c==b''

else lambda z: z(byte2lam(c[0],8) if bytemode else bit2lam(c[0]&1))(input(n+1)))

return inp[n]

def lam2bit(lambit) :

return lambit(lambda _: 0)(lambda _: 1)(0) # force suspension

def lam2byte(lambits, x) :

return lambits(lambda lambit: lambda lamtail: lambda _: lam2byte(lamtail, 2*x+lam2bit(lambit)))(bytes([x]))

def output(prog) :

return prog(lambda c: os.write(1,lam2byte(c,0) if bytemode else (b'1' if lam2bit(c) else b'0')) and (lambda tail: lambda _ : output(tail)))(0)

def getbit() :

global nbit, progchar

if nbit==0 :

progchar = os.read(0,1)[0]

nbit = 8 if bytemode else 1

nbit -= 1

return (progchar >> nbit) & 1

def program() :

if getbit() : # variable

i = 0

while (getbit()==1) : i += 1

return lambda *args : args[i]

elif getbit() : # application

p = program()

q = program()

return lambda *args : p(*args)(lambda arg: q(*args)(arg)) # suspend argument

else :

p = program()

return lambda *args: lambda arg: p(arg, *args) # extend environment with one more argument

sys.setrecursionlimit(8192)

inp = []

nbit = progchar = 0

bytemode = len(sys.argv) <= 1

prog = program()(0)

output(prog(input(0))) # run program with empty env on input</syntaxhighlight>