## experimental compiler to translate programs written in a generic
## expression-oriented language called 'lambda' into Mu
# incomplete; code generator not done
# potential enhancements:
# symbol table
# poor man's macros
# substitute one instruction with multiple, parameterized by inputs and products
scenario convert-lambda [
run [
local-scope
1:text/raw <- lambda-to-mu [(add a (multiply b c))]
2:@:char/raw <- copy *1:text/raw
]
memory-should-contain [
2:array:character <- [t1 <- multiply b c
result <- add a t1]
]
]
def lambda-to-mu in:text -> out:text [
local-scope
load-inputs
out <- copy null
cells:&:cell <- parse in
out <- to-mu cells
]
# 'parse' will turn lambda expressions into trees made of cells
exclusive-container cell [
atom:text
pair:pair
]
# printed below as < first | rest >
container pair [
first:&:cell
rest:&:cell
]
def new-atom name:text -> result:&:cell [
local-scope
load-inputs
result <- new cell:type
*result <- merge 0/tag:atom, name
]
def new-pair a:&:cell, b:&:cell -> result:&:cell [
local-scope
load-inputs
result <- new cell:type
*result <- merge 1/tag:pair, a/first, b/rest
]
def is-atom? x:&:cell -> result:bool [
local-scope
load-inputs
return-unless x, false
_, result <- maybe-convert *x, atom:variant
]
def is-pair? x:&:cell -> result:bool [
local-scope
load-inputs
return-unless x, false
_, result <- maybe-convert *x, pair:variant
]
scenario atom-is-not-pair [
local-scope
s:text <- new [a]
x:&:cell <- new-atom s
10:bool/raw <- is-atom? x
11:bool/raw <- is-pair? x
memory-should-contain [
10 <- 1
11 <- 0
]
]
scenario pair-is-not-atom [
local-scope
# construct (a . nil)
s:text <- new [a]
x:&:cell <- new-atom s
y:&:cell <- new-pair x, null
10:bool/raw <- is-atom? y
11:bool/raw <- is-pair? y
memory-should-contain [
10 <- 0
11 <- 1
]
]
def atom-match? x:&:cell, pat:text -> result:bool [
local-scope
load-inputs
s:text, is-atom?:bool <- maybe-convert *x, atom:variant
return-unless is-atom?, false
result <- equal pat, s
]
scenario atom-match [
local-scope
x:&:cell <- new-atom [abc]
10:bool/raw <- atom-match? x, [abc]
memory-should-contain [
10 <- 1
]
]
def first x:&:cell -> result:&:cell [
local-scope
load-inputs
pair:pair, pair?:bool <- maybe-convert *x, pair:variant
return-unless pair?, null
result <- get pair, first:offset
]
def rest x:&:cell -> result:&:cell [
local-scope
load-inputs
pair:pair, pair?:bool <- maybe-convert *x, pair:variant
return-unless pair?, null
result <- get pair, rest:offset
]
def set-first base:&:cell, new-first:&:cell -> base:&:cell [
local-scope
load-inputs
pair:pair, is-pair?:bool <- maybe-convert *base, pair:variant
return-unless is-pair?
pair <- put pair, first:offset, new-first
*base <- merge 1/pair, pair
]
def set-rest base:&:cell, new-rest:&:cell -> base:&:cell [
local-scope
load-inputs
pair:pair, is-pair?:bool <- maybe-convert *base, pair:variant
return-unless is-pair?
pair <- put pair, rest:offset, new-rest
*base <- merge 1/pair, pair
]
scenario cell-operations-on-atom [
local-scope
s:text <- new [a]
x:&:cell <- new-atom s
10:&:cell/raw <- first x
11:&:cell/raw <- rest x
memory-should-contain [
10 <- 0 # first is nil
11 <- 0 # rest is nil
]
]
scenario cell-operations-on-pair [
local-scope
# construct (a . nil)
s:text <- new [a]
x:&:cell <- new-atom s
y:&:cell <- new-pair x, null
x2:&:cell <- first y
10:bool/raw <- equal x, x2
11:&:cell/raw <- rest y
memory-should-contain [
10 <- 1 # first is correct
11 <- 0 # rest is nil
]
]
## convert lambda text to a tree of cells
def parse in:text -> out:&:cell [
local-scope
load-inputs
s:&:stream:char <- new-stream in
out, s <- parse s
trace 2, [app/parse], out
]
def parse in:&:stream:char -> out:&:cell, in:&:stream:char [
local-scope
load-inputs
# skip whitespace
in <- skip-whitespace in
c:char, eof?:bool <- peek in
return-if eof?, null
pair?:bool <- equal c, 40/open-paren
{
break-if pair?
# atom
buf:&:buffer:char <- new-buffer 30
{
done?:bool <- end-of-stream? in
break-if done?
# stop before close paren or space
c:char <- peek in
done? <- equal c, 41/close-paren
break-if done?
done? <- space? c
break-if done?
c <- read in
buf <- append buf, c
loop
}
s:text <- buffer-to-array buf
out <- new-atom s
}
{
break-unless pair?
# pair
read in # skip the open-paren
out <- new cell:type # start out with nil
# read in first element of pair
{
end?:bool <- end-of-stream? in
not-end?:bool <- not end?
assert not-end?, [unbalanced '(' in expression]
c <- peek in
close-paren?:bool <- equal c, 41/close-paren
break-if close-paren?
first:&:cell, in <- parse in
*out <- merge 1/pair, first, null
}
# read in any remaining elements
curr:&:cell <- copy out
{
in <- skip-whitespace in
end?:bool <- end-of-stream? in
not-end?:bool <- not end?
assert not-end?, [unbalanced '(' in expression]
# termination check: ')'
c <- peek in
{
close-paren?:bool <- equal c, 41/close-paren
break-unless close-paren?
read in # skip ')'
break +end-pair
}
# still here? read next element of pair
next:&:cell, in <- parse in
is-dot?:bool <- atom-match? next, [.]
{
break-if is-dot?
next-curr:&:cell <- new-pair next, null
curr <- set-rest curr, next-curr
curr <- rest curr
}
{
break-unless is-dot?
# deal with dotted pair
in <- skip-whitespace in
c <- peek in
not-close-paren?:bool <- not-equal c, 41/close-paren
assert not-close-paren?, [')' cannot immediately follow '.']
final:&:cell <- parse in
curr <- set-rest curr, final
# we're not gonna update curr, so better make sure the next iteration
# is going to end the pair
in <- skip-whitespace in
c <- peek in
close-paren?:bool <- equal c, 41/close-paren
assert close-paren?, ['.' must be followed by exactly one expression before ')']
}
loop
}
+end-pair
}
]
def skip-whitespace in:&:stream:char -> in:&:stream:char [
local-scope
load-inputs
{
done?:bool <- end-of-stream? in
return-if done?, null
c:char <- peek in
space?:bool <- space? c
break-unless space?
read in # skip
loop
}
]
def to-text x:&:cell -> out:text [
local-scope
load-inputs
buf:&:buffer:char <- new-buffer 30
buf <- to-buffer x, buf
out <- buffer-to-array buf
]
def to-buffer x:&:cell, buf:&:buffer:char -> buf:&:buffer:char [
local-scope
load-inputs
# base case: empty cell
{
break-if x
buf <- append buf, [<>]
return
}
# base case: atom
{
s:text, atom?:bool <- maybe-convert *x, atom:variant
break-unless atom?
buf <- append buf, s
return
}
# recursive case: pair
buf <- append buf, [< ]
first:&:cell <- first x
buf <- to-buffer first, buf
buf <- append buf, [ | ]
rest:&:cell <- rest x
buf <- to-buffer rest, buf
buf <- append buf, [ >]
]
scenario parse-single-letter-atom [
local-scope
s:text <- new [a]
x:&:cell <- parse s
s2:text, 10:bool/raw <- maybe-convert *x, atom:variant
11:@:char/raw <- copy *s2
memory-should-contain [
10 <- 1 # parse result is an atom
11:array:character <- [a]
]
]
scenario parse-atom [
local-scope
s:text <- new [abc]
x:&:cell <- parse s
s2:text, 10:bool/raw <- maybe-convert *x, atom:variant
11:@:char/raw <- copy *s2
memory-should-contain [
10 <- 1 # parse result is an atom
11:array:character <- [abc]
]
]
scenario parse-list-of-two-atoms [
local-scope
s:text <- new [(abc def)]
x:&:cell <- parse s
trace-should-contain [
app/parse: < abc | < def | <> > >
]
10:bool/raw <- is-pair? x
x1:&:cell <- first x
x2:&:cell <- rest x
s1:text, 11:bool/raw <- maybe-convert *x1, atom:variant
12:bool/raw <- is-pair? x2
x3:&:cell <- first x2
s2:text, 13:bool/raw <- maybe-convert *x3, atom:variant
14:&:cell/raw <- rest x2
20:@:char/raw <- copy *s1
30:@:char/raw <- copy *s2
memory-should-contain [
10 <- 1 # parse result is a pair
11 <- 1 # result.first is an atom
12 <- 1 # result.rest is a pair
13 <- 1 # result.rest.first is an atom
14 <- 0 # result.rest.rest is nil
20:array:character <- [abc] # result.first
30:array:character <- [def] # result.rest.first
]
]
scenario parse-list-with-extra-spaces [
local-scope
s:text <- new [ ( abc def ) ] # extra spaces
x:&:cell <- parse s
trace-should-contain [
app/parse: < abc | < def | <> > >
]
10:bool/raw <- is-pair? x
x1:&:cell <- first x
x2:&:cell <- rest x
s1:text, 11:bool/raw <- maybe-convert *x1, atom:variant
12:bool/raw <- is-pair? x2
x3:&:cell <- first x2
s2:text, 13:bool/raw <- maybe-convert *x3, atom:variant
14:&:cell/raw <- rest x2
20:@:char/raw <- copy *s1
30:@:char/raw <- copy *s2
memory-should-contain [
10 <- 1 # parse result is a pair
11 <- 1 # result.first is an atom
12 <- 1 # result.rest is a pair
13 <- 1 # result.rest.first is an atom
14 <- 0 # result.rest.rest is nil
20:array:character <- [abc] # result.first
30:array:character <- [def] # result.rest.first
]
]
scenario parse-list-of-more-than-two-atoms [
local-scope
s:text <- new [(abc def ghi)]
x:&:cell <- parse s
trace-should-contain [
app/parse: < abc | < def | < ghi | <> > > >
]
10:bool/raw <- is-pair? x
x1:&:cell <- first x
x2:&:cell <- rest x
s1:text, 11:bool/raw <- maybe-convert *x1, atom:variant
12:bool/raw <- is-pair? x2
x3:&:cell <- first x2
s2:text, 13:bool/raw <- maybe-convert *x3, atom:variant
x4:&:cell <- rest x2
14:bool/raw <- is-pair? x4
x5:&:cell <- first x4
s3:text, 15:bool/raw <- maybe-convert *x5, atom:variant
16:&:cell/raw <- rest x4
20:@:char/raw <- copy *s1
30:@:char/raw <- copy *s2
40:@:char/raw <- copy *s3
memory-should-contain [
10 <- 1 # parse result is a pair
11 <- 1 # result.first is an atom
12 <- 1 # result.rest is a pair
13 <- 1 # result.rest.first is an atom
14 <- 1 # result.rest.rest is a pair
15 <- 1 # result.rest.rest.first is an atom
16 <- 0 # result.rest.rest.rest is nil
20:array:character <- [abc] # result.first
30:array:character <- [def] # result.rest.first
40:array:character <- [ghi] # result.rest.rest
]
]
scenario parse-nested-list [
local-scope
s:text <- new [((abc))]
x:&:cell <- parse s
trace-should-contain [
app/parse: < < abc | <> > | <> >
]
10:bool/raw <- is-pair? x
x1:&:cell <- first x
11:bool/raw <- is-pair? x
x2:&:cell <- first x1
s1:text, 12:bool/raw <- maybe-convert *x2, atom:variant
13:&:cell/raw <- rest x1
14:&:cell/raw <- rest x
20:@:char/raw <- copy *s1
memory-should-contain [
10 <- 1 # parse result is a pair
11 <- 1 # result.first is a pair
12 <- 1 # result.first.first is an atom
13 <- 0 # result.first.rest is nil
14 <- 0 # result.rest is nil
20:array:character <- [abc] # result.first.first
]
]
scenario parse-nested-list-2 [
local-scope
s:text <- new [((abc) def)]
x:&:cell <- parse s
trace-should-contain [
app/parse: < < abc | <> > | < def | <> > >
]
10:bool/raw <- is-pair? x
x1:&:cell <- first x
11:bool/raw <- is-pair? x
x2:&:cell <- first x1
s1:text, 12:bool/raw <- maybe-convert *x2, atom:variant
13:&:cell/raw <- rest x1
x3:&:cell <- rest x
x4:&:cell <- first x3
s2:text, 14:bool/raw <- maybe-convert *x4, atom:variant
15:&:cell/raw <- rest x3
20:@:char/raw <- copy *s1
30:@:char/raw <- copy *s2
memory-should-contain [
10 <- 1 # parse result is a pair
11 <- 1 # result.first is a pair
12 <- 1 # result.first.first is an atom
13 <- 0 # result.first.rest is nil
14 <- 1 # result.rest.first is an atom
15 <- 0 # result.rest.rest is nil
20:array:character <- [abc] # result.first.first
30:array:character <- [def] # result.rest.first
]
]
# todo: uncomment these tests after we figure out how to continue tests after
# assertion failures
#? scenario parse-error [
#? local-scope
#? s:text <- new [(]
#? #? hide-errors
#? x:&:cell <- parse s
#? #? show-errors
#? trace-should-contain [
#? error: unbalanced '(' in expression
#? ]
#? ]
#?
#? scenario parse-error-after-element [
#? local-scope
#? s:text <- new [(abc]
#? #? hide-errors
#? x:&:cell <- parse s
#? #? show-errors
#? trace-should-contain [
#? error: unbalanced '(' in expression
#? ]
#? ]
scenario parse-dotted-list-of-two-atoms [
local-scope
s:text <- new [(abc . def)]
x:&:cell <- parse s
trace-should-contain [
app/parse: < abc | def >
]
10:bool/raw <- is-pair? x
x1:&:cell <- first x
x2:&:cell <- rest x
s1:text, 11:bool/raw <- maybe-convert *x1, atom:variant
s2:text, 12:bool/raw <- maybe-convert *x2, atom:variant
20:@:char/raw <- copy *s1
30:@:char/raw <- copy *s2
memory-should-contain [
# parses to < abc | def >
10 <- 1 # parse result is a pair
11 <- 1 # result.first is an atom
12 <- 1 # result.rest is an atom
20:array:character <- [abc] # result.first
30:array:character <- [def] # result.rest
]
]
scenario parse-dotted-list-of-more-than-two-atoms [
local-scope
s:text <- new [(abc def . ghi)]
x:&:cell <- parse s
trace-should-contain [
app/parse: < abc | < def | ghi > >
]
10:bool/raw <- is-pair? x
x1:&:cell <- first x
x2:&:cell <- rest x
s1:text, 11:bool/raw <- maybe-convert *x1, atom:variant
12:bool/raw <- is-pair? x2
x3:&:cell <- first x2
s2:text, 13:bool/raw <- maybe-convert *x3, atom:variant
x4:&:cell <- rest x2
s3:text, 14:bool/raw <- maybe-convert *x4, atom:variant
20:@:char/raw <- copy *s1
30:@:char/raw <- copy *s2
40:@:char/raw <- copy *s3
memory-should-contain [
10 <- 1 # parse result is a pair
11 <- 1 # result.first is an atom
12 <- 1 # result.rest is a pair
13 <- 1 # result.rest.first is an atom
14 <- 1 # result.rest.rest is an atom
20:array:character <- [abc] # result.first
30:array:character <- [def] # result.rest.first
40:array:character <- [ghi] # result.rest.rest
]
]
## convert tree of cells to Mu text
def to-mu in:&:cell -> out:text [
local-scope
load-inputs
buf:&:buffer:char <- new-buffer 30
buf <- to-mu in, buf
out <- buffer-to-array buf
]
def to-mu in:&:cell, buf:&:buffer:char -> buf:&:buffer:char, result-name:text [
local-scope
load-inputs
# null cell? no change.
# pair with all atoms? gensym a new variable
# pair containing other pairs? recurse
result-name <- copy null
]