LambdaPython

LambdaPython is Python, but if your program includes def, it raises a syntax error (that means you must use built-in functions or lambda functions instead of normal ones, thus the name). It is named by User:None1 and inspired by UnnumericJS which is inspired by MangularJS.

Examples

Most programs are the same (as Python), but here is an example that computes the n-th Fibonacci number using recursion (reads n and outputs the n-th Fibonacci number):

exec('\x64\x65\x66\x20\x66\x69\x62\x28\x6e\x29\x3a\x0a\x09\x69\x66\x20\x6e\x3d\x3d\x30\x3a\x0a\x09\x09\x72\x65\x74\x75\x72\x6e\x20\x30\x0a\x09\x69\x66\x20\x6e\x3d\x3d\x31\x3a\x0a\x09\x09\x72\x65\x74\x75\x72\x6e\x20\x31\x0a\x09\x72\x65\x74\x75\x72\x6e\x28\x66\x69\x62\x28\x6e\x2d\x31\x29\x2b\x66\x69\x62\x28\x6e\x2d\x32\x29\x29\x0a\x70\x72\x69\x6e\x74\x28\x66\x69\x62\x28\x69\x6e\x74\x28\x69\x6e\x70\x75\x74\x28\x29\x29\x29\x29')

Athough it uses recursion, it does not include def, so it is still allowed.

Alternatively, every def can be transformed into a lambda. The above Fibonacci function can be expressed as:

f = lambda n: 0 if n == 0 else 1 if n == 1 else f(n - 1) + f(n - 2)

Here is a lambda-only version of an iterative Fibonacci function which doesn't use recursion:

f = lambda i, l=[0, 1]: [l.append(l[-1] + l[-2]) for _ in range(i + 1 - len(l))] and l[i]

Interpreter in Python

import sys
code=sys.stdin.read()
if 'def' in code:
    raise Exception('Syntax error')
else:
    exec(code)

Self interpreter

import sys
code=sys.stdin.read()
if '\x64\x65\x66' in code:
    raise Exception('Syntax error')
else:
    exec(code)

This is also an interpreter in Python.

Turing completeness

We can use exec() and the hexadecimal escape to run any Python code, so it is Turing complete.