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feat: sequencing of expressions with newline to same indent (#11)

feat: sequencing of expressions with newline to same indent

  Also revised README to reflect greater emphasis on streams.
  Haskell code generation unsurprisingly required a fairly significant
  rework.

  Resolves #3.

Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Reviewed-on: #11
Co-Authored-By: Glen Whitney <glen@nobody@nowhere.net>
Co-Committed-By: Glen Whitney <glen@nobody@nowhere.net>
semi_separate
Glen Whitney 10 months ago
parent
commit
991976d3a8
  1. 17
      README.md
  2. 1
      metaborg.yaml
  3. 30
      syntax/fostr.sdf3
  4. 90
      tests/basic.spt
  5. 2
      tests/emit_sum.fos
  6. 5
      tests/emit_thrice.fos
  7. 31
      trans/haskell.str
  8. 19
      trans/javascript.str
  9. 21
      trans/python.str
  10. 4
      trans/util.str

17
README.md

@ -8,9 +8,12 @@ dimensions.
So I embarked on this project to see if I could produce as comfortable a
language as possible to work in, given that I inevitably will be doing a
bunch of coding. The language will be
organized around (unary) ++f++unctions, (binary) ++o++perators, and
(nullary) ++str++eams, hence the name "fostr".
bunch of coding. The language will be centrally organized around the
concept of "streams" (somewhat in the spirit of
[streem](https://github.com/matz/streem) and/or
[Orc](http://orc.csres.utexas.edu/index.shtml)). In fact all higher-type
entities will be cast in terms of streams, or in slogan form, "++f++unctions
and (binary) ++o++perators are ++str++eams" (hence the name "fostr").
Other guiding principles:
@ -24,11 +27,9 @@ Other guiding principles:
the language design from the ground up, it can be kept both effective and
natural.
* Code uses functions all the time. So needless to say, functions should be
first-class entities that are exceptionally easy to create, pass around,
etc.
* And true to the name, operators and streams should be just as easy to handle.
* fostr code uses streams (and their specializations to functions and
operators) all the time, so they are first-class entities that are easy
to create, pass around, compose, etc.
* Try to keep the constructs available as simple to reason about as possible,
and practical to use. So side effects are OK, and it should be clear when

1
metaborg.yaml

@ -19,6 +19,7 @@ language:
sdf:
pretty-print: fostr
sdf2table: java
jsglr-version: layout-sensitive
placeholder:
prefix: "$"
stratego:

30
syntax/fostr.sdf3

@ -10,28 +10,34 @@ context-free start-symbols
context-free sorts
Start Ex
Start LineSeq Line Ex
context-free syntax
Start.TopLevel = prog:Ex {layout(offside prog)}
Start.TopLevel = LineSeq
LineSeq = <<ln:Ex>> {layout(offside ln)}
LineSeq.Sequence = sq:Ex+ {layout(align-list sq)}
Ex+ = Ex+ ln:Ex {layout(offside ln)}
Ex.Int = INT
Ex.Stdio = <stdio>
Ex.Sum = {Ex "+"}+
Ex.Receives = [[Ex] << [Ex]] {left}
Ex.Enters = [[Ex] >> [Ex]] {left}
Ex.Stream = <stream>
Ex.Sum = [[Ex] + [Ex]] {left}
Ex.Gets = [[Ex] << [Ex]] {left}
Ex.To = [[Ex] >> [Ex]] {left}
Ex = <(<Ex>)> {bracket}
context-free priorities
Ex.Enters
Ex.To
> Ex.Sum
> Ex.Receives,
> Ex.Gets,
// prevent cycle: no singletons
Ex.Sum <0> .> {Ex "+"}+ = Ex,
LineSeq.Sequence <0> .> Ex+ = Ex,
// flat: no Sum immediately in Sum:
{Ex "+"}+ = Ex <0> .> Ex.Sum,
{Ex "+"}+ = {Ex "+"}+ "+" Ex <2> .> Ex.Sum
// flat: No LineSeq immediately in LineSeq
Ex+ = Ex <0> .> LineSeq.Sequence,
Ex+ = Ex+ Ex <1> .> LineSeq.Sequence

90
tests/basic.spt

@ -13,9 +13,9 @@ that writes the sum of the ASCII codes for 'H', 'W', and '!' to standard output:
**/
/** md */ test emit_sum [[
stdio << 72 + 87 + 33
]]/* **/ parse to TopLevel(Receives(Stdio(),
Sum([Int("72"), Int("87"), Int("33")])))
stream << 72 + 87 + 33
]]/* **/ parse to TopLevel(Gets(Stream(),
Sum(Sum(Int("72"), Int("87")), Int("33"))))
/** writes
192**/
@ -40,32 +40,27 @@ For example, this snippet generates the following Python:
start: 'Stdio\s='
!}
```
(which writes "192" to standard output), or this non-idiomatic, inefficient, but
working Javascript:
```javascript
{! ../tests/emit_sum.js extract:
start: '^}'
!}
```
In either case, there's also a preamble defining Stdio that's generated.
(Haskell code generation is also currently supported.)
(which writes "192" to standard output); it also generates identical code in
this simple example for
Javascript, although it generates a different preamble defining Stdio in each
case. (Haskell code generation is also currently supported.)
### Everything has a value
As mentioned in the [Introduction](../README.md), everything in a fostr
program (including the entire program itself) is an expression and has
a value. So what's the value of that expression above? Well, `stdio` is our
a value. So what's the value of that expression above? Well, appropriately
enough, `stream` is our
first example of a stream, and for convenience, the value of a stream
receiving an item is just the stream back again. The `<<` operator is also
left-associative, so that way we can chain insertions into a stream:
receiving an item is (usually) just the stream back again. The `<<` operator
is also left-associative, so that way we can chain insertions into a stream:
```fostr
**/
/** md */ test emit_twice [[
stdio << 72 + 87 + 33 << 291
stream << 72 + 87 + 33 << 291
]]/* **/ parse to TopLevel(
Receives(Receives(Stdio(), Sum([Int("72"), Int("87"), Int("33")])),
Int("291")))
Gets(Gets(Stream(), Sum(Sum(Int("72"), Int("87")), Int("33"))), Int("291")))
/** writes
192291**/
@ -75,14 +70,14 @@ Running this program produces a nice palindromic output: "192291".
And because sometimes you want to emphasize the value and propagate that
instead of the stream, you can also write these expressions "the other way"
with `>>`; both forms return the first argument:
with `>>`; both forms return the first argument, so the following writes "824":
```fostr
**/
/** md */ test enters_twice [[
(7 + 8 >> stdio + 9) >> stdio
(7 + 8 >> stream + 9) >> stream
]]/* **/ parse to TopLevel(
Enters(Sum([Int("7"), Enters(Int("8"), Stdio()), Int("9")]), Stdio()))
To(Sum(Sum(Int("7"), To(Int("8"), Stream())), Int("9")), Stream()))
/** writes
824**/
@ -97,12 +92,12 @@ lines are indented from the start of the initial line:
**/
/** md */ test receive_enter_break [[
stdio <<
stream <<
7
+ 8 >> stdio
+ 8 >> stream
+ 9
]]/* **/ parse to TopLevel(
Receives(Stdio(), Sum([Int("7"), Enters(Int("8"), Stdio()), Int("9")])))
Gets(Stream(), Sum(Sum(Int("7"), To(Int("8"), Stream())), Int("9"))))
/** writes
824**/
@ -113,19 +108,56 @@ stdio <<
**/
/** md */ test enter_receive_bad_break [[
(7 + 8 >> stdio + 9)
>> (stdio << 9 + 2)
(7 + 8 >> stream + 9)
>> (stream << 9 + 2)
]] /* **/ parse fails
/* Extra tests not in the tour */
test enter_receive [[
(7 + 8 >> stdio + 9) >> (stdio << 9 + 2)
(7 + 8 >> stream + 9) >> (stream << 9 + 2)
]]/* **/ parse to TopLevel(
Enters(Sum([Int("7"),Enters(Int("8"),Stdio()),Int("9")]),
Receives(Stdio(),Sum([Int("9"),Int("2")]))))
To(Sum(Sum(Int("7"),To(Int("8"),Stream())),Int("9")),
Gets(Stream(),Sum(Int("9"),Int("2")))))
/** writes
81124**/
/** md
```
Of course, fostr programs are not limited to one line; expressions on successive
lines are evaluated in sequence. For example, the program
```fostr
**/
/** md */ test emit_thrice [[
stream << 72 + 87
stream << 88
+ 96
99 + 12 >>
stream
]] /* **/ parse to TopLevel( Sequence(
[ Gets(Stream(), Sum(Int("72"), Int("87")))
, Gets(Stream(), Sum(Int("88"), Int("96")))
, Sum(Int("99"), To(Int("12"), Stream()))]))
/** writes
15918412**/
/** md
```
will write 15918412. fostr enforces that successive expressions in sequence
must line up at the left, i.e., the following will not parse:
```fostr
**/
/** md */ test emit_thrice_bad_alignment [[
stream << 72 + 87
stream << 88
+ 96
99 + 12 >> stream
]] /* **/ parse fails
/** md
```
**/

2
tests/emit_sum.fos

@ -1 +1 @@
stdio << 72 + 87 + 33
stream << 72 + 87 + 33

5
tests/emit_thrice.fos

@ -0,0 +1,5 @@
stream << 72 + 87
stream << 88
+ 96
99 + 12 >>
stream

31
trans/haskell.str

@ -17,33 +17,32 @@ rules
hs: TopLevel((c,p)) -> $[import System.IO
data IOStream = StdIO
stdio :: IO IOStream
stdio = return StdIO
receives :: Show b => IO a -> b -> IO a
receives s d = do
temp <- s
gets :: Show b => a -> b -> IO a
gets s d = do
putStr(show d)
return temp
return s
main = do
[p]return [c]]
hs: Stdio() -> ("stdio", "")
hs: Stream() -> ("StdIO", "")
hs: Int(x) -> (x, "")
hs: Sum((c,p)) -> ($[sum [c]], p)
hs: Receives((c, p), (d, s)) -> ($[[c] `receives` [d]], <conc-strings>(p,s))
hs: Enters((c, p), (d, s)) -> <hsenter>(c,d,<conc-strings>(p,s),<newname>"fos")
hs: Sum( (c, p), (d, q)) -> ($[([c] + [d])], <conc-strings>(p,q))
hs: Gets((c, p), (d, q)) -> <hsget>(c,d,<conc-strings>(p,q),<newname>"fosgt")
hsget: (s, x, p, v) -> (v, <concat-strings>[p, $[[v] <- [s] `gets` [x]],
"\n"])
hs: To( (c, p), (d, q)) -> <hsto>(c,d,<conc-strings>(p,q),<newname>"fosto")
hsenter: (x, s, p, v) -> (v, <concat-strings>[$[[p]let [v] = [x]], "\n",
$[[s] `receives` [v]], "\n"])
hsto: (x, s, p, v) -> (v, <concat-strings>[p, $[let [v] = [x]], "\n",
$[[s] `gets` [v]], "\n"])
hslist: x -> (<map(Fst); join(|", "); brack>x, <map(Snd); concat-strings>x)
brack: x -> $<[<x>]>
hs: Sequence(l) -> (<last; Fst>l, <map(Snd); concat-strings>l)
strategies
haskell = bottomup(try(hs <+ hslist))
haskell = bottomup(try(hs))
// Interface haskell code generation with editor services and file system
to-haskell: (selected, _, _, path, project-path) -> (filename, result)

19
trans/javascript.str

@ -7,25 +7,24 @@ signature
rules
js: TopLevel(x) -> $[const Stdio = {
receives: v => { process.stdout.write(String(v)); return Stdio; },
gets: v => { process.stdout.write(String(v)); return Stdio; },
}
function forwards(data, strm) {
strm.receives(data);
function to(data, strm) {
strm.gets(data);
return data;
}
[x]]
js: Stdio() -> $[Stdio]
js: Stream() -> $[Stdio]
js: Int(x) -> x
js: Sum(x) -> $[[x].reduce((v,w) => v+w)]
js: Receives(x, y) -> $[[x].receives([y])]
js: Enters(x, y) -> $[forwards([x],[y])]
jslist: x -> $<[<<join(|", ")>x>]>
js: Sum(x,y) -> $[[x] + [y]]
js: Gets(x, y) -> $[[x].gets([y])]
js: To(x, y) -> $[to([x],[y])]
js: Sequence(l) -> <join(|";\n")>l
strategies
javascript = bottomup(try(js <+ jslist))
javascript = bottomup(try(js))
// Interface javascript code generation with editor services and file system
to-javascript: (selected, _, _, path, project-path) -> (filename, result)

21
trans/python.str

@ -9,26 +9,25 @@ rules
py: TopLevel(x) -> $[import sys
class StdioC:
def receives(self, v):
def gets(self, v):
print(v, file=sys.stdout, end='')
return self
def forwards(data,strm):
strm.receives(data)
def to(data,strm):
strm.gets(data)
return data
Stdio = StdioC()
[x]]
py: Stdio() -> $[Stdio]
py: Int(x) -> x
py: Sum(x) -> $[sum([x])]
py: Receives(x, y) -> $[[x].receives([y])]
py: Enters(x, y) -> $[forwards([x],[y])]
pylist: x -> $<[<<join(|", ")>x>]>
py: Stream() -> $[Stdio]
py: Int(x) -> x
py: Sum(x,y) -> $[[x] + [y]]
py: Gets(x, y) -> $[[x].gets([y])]
py: To(x, y) -> $[to([x],[y])]
py: Sequence(l) -> <join(|"\n")>l
strategies
python = bottomup(try(py <+ pylist))
python = bottomup(try(py))
// Interface python code generation with editor services and file system
to-python: (selected, _, _, path, project-path) -> (filename, result)

4
trans/util.str

@ -3,7 +3,7 @@ imports libstrategolib
rules
join(|infix) : [] -> ""
join(|infix) : [x | xs] -> $[[x][<prejoin(|infix)>xs]]
join(|infix) : [x | xs] -> <conc-strings>(x, <prejoin(|infix)>xs)
prejoin(|infix) : [] -> ""
prejoin(|infix) : [x | xs] -> $[[infix][x][<prejoin(|infix)>xs]]
prejoin(|infix) : [x | xs] -> <concat-strings>[infix,x,<prejoin(|infix)>xs]

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