Thun/implementations/Python/joy/library.py

438 lines
11 KiB
Python

ALIASES = (
('bool', ['truthy']),
('mod', ['%', 'rem', 'remainder', 'modulus']),
('getitem', ['pick', 'at']),
('xor', ['^']),
('eh', ['?']),
('id', [u'']),
)
def floor(n):
return int(math.floor(n))
floor.__doc__ = math.floor.__doc__
@inscribe
@SimpleFunctionWrapper
def divmod_(S):
'''
divmod(x, y) -> (quotient, remainder)
Return the tuple (x//y, x%y). Invariant: q * y + r == x.
'''
y, (x, stack) = S
q, r = divmod(x, y)
return r, (q, stack)
@inscribe
@SimpleFunctionWrapper
def id_(stack):
'''The identity function.'''
return stack
#
# § Combinators
#
# Several combinators depend on other words in their definitions,
# we use symbols to prevent hard-coding these, so in theory, you
# could change the word in the dictionary to use different semantics.
S_choice = Symbol('choice')
S_first = Symbol('first')
S_genrec = Symbol('genrec')
S_getitem = Symbol('getitem')
S_i = Symbol('i')
S_ifte = Symbol('ifte')
S_infra = Symbol('infra')
S_loop = Symbol('loop')
S_pop = Symbol('pop')
S_primrec = Symbol('primrec')
S_step = Symbol('step')
S_swaack = Symbol('swaack')
S_times = Symbol('times')
#def cleave(S, expression, dictionary):
# '''
# The cleave combinator expects two quotations, and below that an item X.
# It first executes [P], with X on top, and saves the top result element.
# Then it executes [Q], again with X, and saves the top result.
# Finally it restores the stack to what it was below X and pushes the two
# results P(X) and Q(X).
# '''
# (Q, (P, (x, stack))) = S
# p = joy((x, stack), P, dictionary)[0][0]
# q = joy((x, stack), Q, dictionary)[0][0]
# return (q, (p, stack)), expression, dictionary
@inscribe
@FunctionWrapper
def branch(stack, expression, dictionary):
'''
Use a Boolean value to select one of two quoted programs to run.
::
branch == roll< choice i
::
False [F] [T] branch
--------------------------
F
True [F] [T] branch
-------------------------
T
'''
(then, (else_, (flag, stack))) = stack
return stack, concat(then if flag else else_, expression), dictionary
@inscribe
@FunctionWrapper
def ifte(stack, expression, dictionary):
'''
If-Then-Else Combinator
::
... [if] [then] [else] ifte
---------------------------------------------------
... [[else] [then]] [...] [if] infra select i
... [if] [then] [else] ifte
-------------------------------------------------------
... [else] [then] [...] [if] infra first choice i
Has the effect of grabbing a copy of the stack on which to run the
if-part using infra.
'''
(else_, (then, (if_, stack))) = stack
expression = (S_infra, (S_first, (S_choice, (S_i, expression))))
stack = (if_, (stack, (then, (else_, stack))))
return stack, expression, dictionary
@inscribe
@FunctionWrapper
def cond(stack, expression, dictionary):
'''
This combinator works like a case statement. It expects a single quote
on the stack that must contain zero or more condition quotes and a
default quote. Each condition clause should contain a quoted predicate
followed by the function expression to run if that predicate returns
true. If no predicates return true the default function runs.
It works by rewriting into a chain of nested `ifte` expressions, e.g.::
[[[B0] T0] [[B1] T1] [D]] cond
-----------------------------------------
[B0] [T0] [[B1] [T1] [D] ifte] ifte
'''
conditions, stack = stack
if conditions:
expression = _cond(conditions, expression)
try:
# Attempt to preload the args to first ifte.
(P, (T, (E, expression))) = expression
except ValueError:
# If, for any reason, the argument to cond should happen to contain
# only the default clause then this optimization will fail.
pass
else:
stack = (E, (T, (P, stack)))
return stack, expression, dictionary
def _cond(conditions, expression):
(clause, rest) = conditions
if not rest: # clause is [D]
return clause
P, T = clause
return (P, (T, (_cond(rest, ()), (S_ifte, expression))))
@inscribe
@FunctionWrapper
def dip(stack, expression, dictionary):
'''
The dip combinator expects a quoted program on the stack and below it
some item, it hoists the item into the expression and runs the program
on the rest of the stack.
::
... x [Q] dip
-------------------
... Q x
'''
try:
(quote, (x, stack)) = stack
except ValueError:
raise StackUnderflowError('Not enough values on stack.')
expression = (x, expression)
return stack, concat(quote, expression), dictionary
@inscribe
@FunctionWrapper
def dipd(S, expression, dictionary):
'''
Like dip but expects two items.
::
... y x [Q] dip
---------------------
... Q y x
'''
(quote, (x, (y, stack))) = S
expression = (y, (x, expression))
return stack, concat(quote, expression), dictionary
@inscribe
@FunctionWrapper
def dipdd(S, expression, dictionary):
'''
Like dip but expects three items.
::
... z y x [Q] dip
-----------------------
... Q z y x
'''
(quote, (x, (y, (z, stack)))) = S
expression = (z, (y, (x, expression)))
return stack, concat(quote, expression), dictionary
@inscribe
@FunctionWrapper
def app1(S, expression, dictionary):
'''
Given a quoted program on TOS and anything as the second stack item run
the program and replace the two args with the first result of the
program.
::
... x [Q] . app1
-----------------------------------
... [x ...] [Q] . infra first
'''
(quote, (x, stack)) = S
stack = (quote, ((x, stack), stack))
expression = (S_infra, (S_first, expression))
return stack, expression, dictionary
@inscribe
@FunctionWrapper
def app2(S, expression, dictionary):
'''Like app1 with two items.
::
... y x [Q] . app2
-----------------------------------
... [y ...] [Q] . infra first
[x ...] [Q] infra first
'''
(quote, (x, (y, stack))) = S
expression = (S_infra, (S_first,
((x, stack), (quote, (S_infra, (S_first,
expression))))))
stack = (quote, ((y, stack), stack))
return stack, expression, dictionary
@inscribe
@FunctionWrapper
def app3(S, expression, dictionary):
'''Like app1 with three items.
::
... z y x [Q] . app3
-----------------------------------
... [z ...] [Q] . infra first
[y ...] [Q] infra first
[x ...] [Q] infra first
'''
(quote, (x, (y, (z, stack)))) = S
expression = (S_infra, (S_first,
((y, stack), (quote, (S_infra, (S_first,
((x, stack), (quote, (S_infra, (S_first,
expression))))))))))
stack = (quote, ((z, stack), stack))
return stack, expression, dictionary
@inscribe
@FunctionWrapper
def step(S, expression, dictionary):
'''
Run a quoted program on each item in a sequence.
::
... [] [Q] . step
-----------------------
... .
... [a] [Q] . step
------------------------
... a . Q
... [a b c] [Q] . step
----------------------------------------
... a . Q [b c] [Q] step
The step combinator executes the quotation on each member of the list
on top of the stack.
'''
(quote, (aggregate, stack)) = S
if not aggregate:
return stack, expression, dictionary
head, tail = aggregate
stack = quote, (head, stack)
if tail:
expression = tail, (quote, (S_step, expression))
expression = S_i, expression
return stack, expression, dictionary
@inscribe
@FunctionWrapper
def times(stack, expression, dictionary):
'''
times == [-- dip] cons [swap] infra [0 >] swap while pop
::
... n [Q] . times
--------------------- w/ n <= 0
... .
... 1 [Q] . times
-----------------------
... . Q
... n [Q] . times
------------------------------------- w/ n > 1
... . Q (n - 1) [Q] times
'''
# times == [-- dip] cons [swap] infra [0 >] swap while pop
(quote, (n, stack)) = stack
if n <= 0:
return stack, expression, dictionary
n -= 1
if n:
expression = n, (quote, (S_times, expression))
expression = concat(quote, expression)
return stack, expression, dictionary
# The current definition above works like this:
# [P] [Q] while
# --------------------------------------
# [P] nullary [Q [P] nullary] loop
# while == [pop i not] [popop] [dudipd] tailrec
#def while_(S, expression, dictionary):
# '''[if] [body] while'''
# (body, (if_, stack)) = S
# while joy(stack, if_, dictionary)[0][0]:
# stack = joy(stack, body, dictionary)[0]
# return stack, expression, dictionary
@inscribe
@FunctionWrapper
def loop(stack, expression, dictionary):
'''
Basic loop combinator.
::
... True [Q] loop
-----------------------
... Q [Q] loop
... False [Q] loop
------------------------
...
'''
try:
quote, stack = stack
except ValueError:
raise StackUnderflowError('Not enough values on stack.')
if not isinstance(quote, tuple):
raise NotAListError('Loop body not a list.')
try:
(flag, stack) = stack
except ValueError:
raise StackUnderflowError('Not enough values on stack.')
if flag:
expression = concat(quote, (quote, (S_loop, expression)))
return stack, expression, dictionary
@inscribe
@FunctionWrapper
def cmp_(stack, expression, dictionary):
'''
cmp takes two values and three quoted programs on the stack and runs
one of the three depending on the results of comparing the two values:
::
a b [G] [E] [L] cmp
------------------------- a > b
G
a b [G] [E] [L] cmp
------------------------- a = b
E
a b [G] [E] [L] cmp
------------------------- a < b
L
'''
L, (E, (G, (b, (a, stack)))) = stack
expression = concat(G if a > b else L if a < b else E, expression)
return stack, expression, dictionary
# FunctionWrapper(cleave),
# FunctionWrapper(while_),
for name, primitive in getmembers(genlib, isfunction):
inscribe(SimpleFunctionWrapper(primitive))