Tiny stack-based language in python.

tinystackr3.py

stack = []
compileStacks = []
words = {}
builtins = {}
lambdaType = type(lambda x: x) #cannot compare against the function type directly for some reason

def prn(o):
	print(o)

def clr(l):
	del l[:]

def is_num(x):
	try:
		float(x)
		return True
	except:
		return False

def can_hash(x):
	try:
		x in {}
		return True
	except:
		return False

def is_str(x):
	return type(x) is str and len(x) > 2 and x.startswith("\"") and x.endswith("\"")

def unquote(x):
	return x[1:len(x) - 1]

def wreduce(word):
	if word == ":":
		compileStacks.append([])
		return []
	elif word == ";":
		compileStacks[len(compileStacks) - 2].append(compileStacks.pop())
		return []
	elif type(word) is str and word.startswith("$"):
		words[word[1:]] = compileStacks[len(compileStacks) - 1].pop()
		return []
	elif is_num(word):
		return [float(word)]
	elif is_str(word):
		return [word]
	elif can_hash(word):
		if word in words:
			return words[word]
		elif word in builtins:
			return [builtins[word]]
	print("wred unknown word " + str(word))

def lcompile(line):
	for word in line.split(" "):
		compileStacks[len(compileStacks) - 1].extend(wreduce(word))

def run(l):
	for w in l:
		if isinstance(w, float) or isinstance(w, list):
			stack.append(w)
		elif is_str(w):
			stack.append(unquote(w))
		elif type(w) == lambdaType:
			w(stack)
		else:
			print("unknown word " + str(w))

builtins["."]    = lambda stack: prn(stack[len(stack) - 1])
builtins[".s"]   = lambda stack: prn(str(stack))
builtins["pop"]  = lambda stack: stack.pop()
builtins["cls"]  = lambda stack: clr(stack)
builtins["dup"]  = lambda stack: stack.append(stack[len(stack) - 1])
builtins["swap"] = lambda stack: stack.append(stack.pop(len(stack) - 2))
builtins["+"]    = lambda stack: stack.append(stack.pop() + stack.pop())
builtins["-"]    = lambda stack: stack.append(-(stack.pop() - stack.pop()))
builtins["*"]    = lambda stack: stack.append(stack.pop() * stack.pop())
builtins["/"]    = lambda stack: stack.append(1/(stack.pop() / stack.pop()))
builtins["call"] = lambda stack: run(stack.pop())
builtins["bra"]  = lambda stack: (run(stack.pop()) if stack.pop() else stack.pop())

while True:
	if len(compileStacks) == 0:
		compileStacks.append([])
	lcompile(raw_input())
	if len(compileStacks) == 1:
		run(compileStacks[0])
		clr(compileStacks)