def evaluate_sequence(actions, environment):
if is_null(actions):
raise SyntaxError("Empty sequence")
if is_null(cdr(actions)):
return g.eval(car(actions), environment)
g.eval(car(actions), environment)
return evaluate_sequence(cdr(actions), environment)
def expand(clauses):
if is_null(clauses):
raise ValueError("COND: no values matched")
if is_else_clause(car(clauses)):
if is_null(cdr(clauses)):
return cond_clause_consequent(car(clauses))
else:
raise SyntaxError(f"COND: ELSE not last {cond_exp}")
return make_if(
cond_clause_predicate(car(clauses)),
cond_clause_consequent(car(clauses)),
expand(cdr(clauses)),
)
def display_pair(p, parens=True):
if parens:
print("(", end="")
display(car(p))
if is_null(cdr(p)):
# no more items
pass
elif is_pair(cdr(p)):
print(" ", end="")
display_pair(cdr(p), parens=False)
else:
print(" . ", end="")
display(cdr(p))
if parens:
print(")", end="")
def sequence_begin(seq):
if is_null(seq):
return seq
if is_null(cdr(seq)):
return car(seq)
actions = tuple(
map(lambda exp: begin_actions(exp) if is_begin(exp) else (exp, ), seq))
return make_begin(tuple(item for sublist in actions for item in sublist))
def loop(alts=alternative_execs):
if is_pair(alts):
return continue_with(
car(alts),
env,
succeed,
lambda *args: continue_with(loop, cdr(alts)),
)
else:
return continue_with(fail)
def begin_actions(begin_exp):
return cdr(begin_exp)
def operands(exp):
return cdr(exp)
def amb_alternatives(exp):
return cdr(exp)
def is_lazy_memo(var_decl):
return (is_pair(var_decl) and memq(symbol("lazy"), cdr(var_decl))
and memq(symbol("memo"), cdr(var_decl)))
def cond_clauses(exp):
return cdr(exp)
def cond_clause_consequent(clause):
return sequence_begin(cdr(clause))
def initialize_repl():
global THE_GLOBAL_ENVIRONMENT
THE_GLOBAL_ENVIRONMENT = make_initial_environment()
def check_repl_initialized():
if THE_GLOBAL_ENVIRONMENT == "not initialized":
raise RuntimeError("Interpreter not initialized. Run init() first.")
if __name__ == "__main__":
a = Symbol("a")
b = Symbol("b")
c = Symbol("c")
print((a, b, c))
print(car((1, 2, 3)), cdr((1, 2, 3)))
x = cons(1, (2, 3, 4))
print(x)
print(car(x), cdr(x), cdr(cdr(x)))
quote = Symbol("quote")
x = Symbol("x")
begin = Symbol("begin")
# print(g.eval(((Symbol('lambda'), (x,), x), 42), ()))
print(g.eval((begin, 1, 2, 3), ()))
init()