forked from glen/fostr
Add literal string constants (#19)
In addition, for the sake of Haskell code generation, this PR adds static typing with Statix. Resolves #5. Co-authored-by: Glen Whitney <glen@studioinfinity.org> Reviewed-on: glen/fostr#19 Co-Authored-By: Glen Whitney <glen@nobody@nowhere.net> Co-Committed-By: Glen Whitney <glen@nobody@nowhere.net>
This commit is contained in:
parent
c516ed6d7f
commit
2772fd0c5c
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@ -11,7 +11,8 @@ language as possible to work in, given that I inevitably will be doing a
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bunch of coding. The language will be centrally organized around the
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concept of "streams" (somewhat in the spirit of
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[streem](https://github.com/matz/streem) and/or
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[Orc](http://orc.csres.utexas.edu/index.shtml)). In fact all higher-type
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[Orc](http://orc.csres.utexas.edu/index.shtml), or to a lesser extent,
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[Sisal-is](https://github.com/parsifal-47/sisal-is)). In fact all higher-type
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entities will be cast in terms of streams, or in slogan form, "++f++unctions
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and (binary) ++o++perators are ++str++eams" (hence the name "fostr").
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@ -27,9 +27,9 @@ for path in TEST_LIST:
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if pfm: continue # skip examples that don't parse
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ntfm = re.search(r'\n\s*\]\].*?don.t.test', details)
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if ntfm: continue # explicit skip
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em = re.search(r'\n\s*\]\]', details)
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em = re.search(r'\n\]\]', details)
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if not em: continue
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example = details[:em.start()+1]
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example = details[:em.start()+1].replace('[[','').replace(']]','')
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expath = destdir / f"{name}.{EXT}"
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expath.write_text(example)
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echo Wrote @(expath)
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@ -22,3 +22,4 @@ menus
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action: "Show pre-analyzed AST" = debug-show-pre-analyzed (source)
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action: "Show analyzed AST" = debug-show-analyzed
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action: "Show analyzed type" = debug-show-type
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@ -2,6 +2,7 @@ site_name: fostr language
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nav:
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- README.md
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- tests/basic.md
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- trans/statics.md
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- implementation.md
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plugins:
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@ -0,0 +1 @@
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TYPE.stx
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@ -0,0 +1,7 @@
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module signature/TYPE
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signature
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sorts TYPE // semantic type
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constructors
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INT : TYPE
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STRING : TYPE
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STREAM : TYPE
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@ -0,0 +1,7 @@
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module statics/util
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imports signature/TYPE
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rules
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lastTYPE : list(TYPE) -> TYPE
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lastTYPE([T]) = T.
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lastTYPE([U | TS]) = lastTYPE(TS).
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@ -8,6 +8,14 @@ context-free start-symbols
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Start
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lexical sorts
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STRING_LITERAL
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lexical syntax
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STRING_LITERAL = "'"~[\']*"'"
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context-free sorts
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Start LineSeq Line OptTermEx TermExLst TermEx Ex
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@ -29,13 +37,14 @@ context-free syntax
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TermEx.Terminate = <<Ex>;>
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Ex.Int = INT
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Ex.Stream = <stream>
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Ex.Sum = [[Ex] + [Ex]] {left}
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Ex.Gets = [[Ex] << [Ex]] {left}
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Ex.To = [[Ex] >> [Ex]] {left}
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Ex.Int = INT
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Ex.LitString = STRING_LITERAL
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Ex.Stream = <stream>
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Ex.Sum = <<Ex> + <Ex>> {left}
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Ex.Gets = [[Ex] << [Ex]] {left}
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Ex.To = [[Ex] >> [Ex]] {left}
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Ex = <(<Ex>)> {bracket}
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Ex = <(<Ex>)> {bracket}
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context-free priorities
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@ -1,6 +1,16 @@
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module basic
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language fostr
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test hw1_type [[
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[[stream]] << [['Hello, world! ']] << [[3+2]] << ' times.'
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]]
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run get-type on #1 to STREAM()
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run get-type on #2 to STRING()
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run get-type on #3 to INT()
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run get-type to STREAM()
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/** writes
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Hello, world! 5 times.**/
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/** md
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Title: A whirlwind tour of fostr
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@ -1,4 +1,4 @@
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stream << 72 + 87
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stream << 'Some numbers: '
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stream << 88
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+ 96
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99 + 12 >>
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@ -0,0 +1 @@
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stream << 'Hello, world!'
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@ -1,5 +1,4 @@
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module analysis
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imports
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statixruntime
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@ -51,3 +50,18 @@ rules // Debugging
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debug-show-analyzed: (sel, _, _, path, projp) -> (filename, result)
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with filename := <guarantee-extension(|"analyzed.aterm")> path
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; result := sel
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// Extract the type assigned to a node by Statix
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get-type: node -> type
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where
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// Assigns variable a to be the result of the Statix analysis of the entire program (or throws an error)
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a := <stx-get-ast-analysis <+ fail-msg(|$[no analysis on node [<strip-annos;write-to-string> node]])>;
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// Gets the type of the given node (or throws an error)
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type := <stx-get-ast-type(|a) <+ fail-msg(|$[no type on node [<strip-annos;write-to-string> node]])> node
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fail-msg(|msg) = err-msg(|$[get-type: [msg]]); fail
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// Prints the analyzed type of a selection.
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debug-show-type: (sel, _, _, path, projp) -> (filename, result)
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with filename := <guarantee-extension(|"type.aterm")> path
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; result := <get-type> sel
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@ -1,15 +1,25 @@
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module haskell
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imports libstrategolib signatures/- util
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imports libstrategolib signatures/- signature/TYPE util analysis
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rules
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/* Approach: Generate code from the bottom up.
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At every node, we create a pair of the implementation and
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necessary preamble of IO actions.
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We concatenate preambles as we go up.
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Finally, at the toplevel we emit the preamble before returning the
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final value.
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/* Approach:
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A) We will define a local transformation taking a term with value strings
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at each child to a value string for the node.
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B) We will append IO actions needed to set up for the value progressively
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to a Preactions rule (mapping () to the list of actions). There will
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be a utility `add-preaction` to append a new clause to value of this
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rule.
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C) We will use bottomup-para to traverse the full AST with the
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transformation from A so that we have access to the original expression
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(and get get the Statix-associated type when we need to).
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Hence the transformation in (A) must actually take a pair of
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an (original) term and a term with value strings at each child,
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and be certain to return a value string.
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Finally, at the toplevel we emit the result of <Preactions>() before
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returning the final value.
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*/
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hs: TopLevel((c,p)) -> $[import System.IO
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hs: (_, TopLevel(val)) -> $[import System.IO
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data IOStream = StdIO
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gets :: Show b => a -> b -> IO a
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@ -17,27 +27,61 @@ rules
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putStr(show d)
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return s
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getsStr :: a -> String -> IO a
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getsStr s d = do
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putStr(d)
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return s
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main = do
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[p]return [c]]
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[<Preactions>()]return [val]]
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hs: Stream() -> ("StdIO", "")
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hs: Int(x) -> (x, "")
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hs: Sum( (c, p), (d, q)) -> ($[([c] + [d])], <conc-strings>(p,q))
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hs: (_, Stream()) -> "StdIO"
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hs: (_, Int(x)) -> x
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hs: (_, LitString(x)) -> <haskLitString>x
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hs: (_, Sum(x, y)) -> $[([x] + [y])]
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hs: Gets((c, p), (d, q)) -> <hsget>(c,d,<conc-strings>(p,q),<newname>"fosgt")
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hsget: (s, x, p, v) -> (v, <concat-strings>[p, $[[v] <- [s] `gets` [x]],
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"\n"])
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hs: (Gets(_, xn), Gets(s, x)) -> v
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with v := <newname>"_fostr_get"
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; <add-preactions>[$[[v] <- [<hs_gets>(s, xn, x)]]]
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hs: (To(xn, _), To(x, s)) -> v
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with v := <newname>"_fostr_to"
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; <add-preactions>[$[let [v] = [x]], <hs_gets>(s, xn, v)]
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hs: To( (c, p), (d, q)) -> <hsto>(c,d,<conc-strings>(p,q),<newname>"fosto")
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hsto: (x, s, p, v) -> (v, <concat-strings>[p, $[let [v] = [x]], "\n",
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$[[s] `gets` [v]], "\n"])
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hs_gets: (s, xn, x ) -> $[[s] [<hs_getOp>xn] [x]]
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hs_getOp = get-type; (?STRING() < !"`getsStr`" + !"`gets`")
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hs: Terminate((c,p)) -> ($[[c];;], p)
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hs: Sequence(l) -> (<last; Fst>l, <map(Snd); concat-strings>l)
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hs: (_, Terminate(x)) -> $[[x];;]
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hs: (_, Sequence(l)) -> <last>l
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/* One drawback of using paramorphism is we have to handle lists
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explicitly:
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*/
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hs: (_, []) -> []
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hs: (_, [x | xs]) -> [x | xs]
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/* Another drawback of using paramorphism is at the very leaves we have
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to undouble the tuple:
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*/
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hs: (x, x) -> x where <is-string>x
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/* Characters we need to escape in Haskell string constants */
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Hascape: ['\t' | cs ] -> ['\', 't' | cs ]
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/* I think I can just use ASCII constants for characters... */
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Hascape: [ 0 | cs ] -> ['\', '0' | cs ]
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Hascape: [ 7 | cs ] -> ['\', 'a' | cs ] // Alert
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Hascape: [ 8 | cs ] -> ['\', 'b' | cs ] // Backspace
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Hascape: [ 11 | cs ] -> ['\', 'v' | cs ] // Vertical tab
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Hascape: [ 12 | cs ] -> ['\', 'f' | cs ] // Form feed
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strategies
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haskLitString = un-single-quote
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; string-as-chars(escape-chars(Escape <+ Hascape))
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; double-quote
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haskell = bottomup(try(hs))
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haskell = rules(Preactions: () -> ""); bottomup-para(try(hs))
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/* See "Approach" at top of file */
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add-preactions = newp := <conc-strings>(<Preactions>(), <lines>)
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; rules(Preactions: () -> newp)
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// Interface haskell code generation with editor services and file system
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to-haskell: (selected, _, _, path, project-path) -> (filename, result)
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@ -13,13 +13,25 @@ rules
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js: Stream() -> $[Stdio]
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js: Int(x) -> x
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js: LitString(x) -> <javaLitString>x
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js: Sum(x,y) -> $[[x] + [y]]
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js: Gets(x, y) -> $[[x].gets([y])]
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js: To(x, y) -> $[to([x],[y])]
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js: Terminate(x) -> x
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js: Sequence(l) -> <join(|";\n")>l
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/* Characters we need to escape in Javascript string constants */
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Jscape: ['\t' | cs ] -> ['\', 't' | cs ]
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/* I think I can just use ASCII constants for characters... */
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Jscape: [ 0 | cs ] -> ['\', '0' | cs ]
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Jscape: [ 8 | cs ] -> ['\', 'b' | cs ] // Backspace
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Jscape: [ 11 | cs ] -> ['\', 'v' | cs ] // Vertical tab
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Jscape: [ 12 | cs ] -> ['\', 'f' | cs ] // Form feed
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strategies
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javaLitString = un-single-quote
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; string-as-chars(escape-chars(Escape <+ Jscape))
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; single-quote
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javascript = bottomup(try(js))
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@ -15,6 +15,7 @@ rules
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py: Stream() -> $[Stdio]
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py: Int(x) -> x
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py: LitString(x) -> $[r[x]]
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py: Sum(x,y) -> $[[x] + [y]]
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py: Gets(x, y) -> $[[x].gets([y])]
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py: To(x, y) -> $[to([x],[y])]
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@ -1,14 +1,257 @@
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module statics
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imports signatures/fostr-sig
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imports signature/TYPE
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imports statics/util
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// see docs/implementation.md for details on how to switch to multi-file analysis
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/** md
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Title: Adding Program Analysis with Statix
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## Development of fostr static analysis
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This section is more documentation of Spoofax in general and Statix
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in particular than of fostr itself, but is being maintained here in case
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it could be either helpful to someone getting started with Statix or
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helpful in understanding how the static characteristics of fostr were designed.
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As mentioned in the [Overview](../README.md), I don't like to program and a
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corollary of that is never to use a facility unless/until there's a need for
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it. So the first few rudimentary passes at fostr simply declared every program
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to be "OK" from the point of view of Statix:
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```statix
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{! "\git docs/statix_start:trans/statics.stx" extract:
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start: programOk
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stop: (.*TopLevel.*)
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!}
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```
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Then I reached the point at which the grammar was basically just
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```SDF3
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// Start.TopLevel = <Seq>
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// Seq = <Ex>
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// Seq.Sequence = sq:Ex+ {layout(align-list sq)}
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// Ex.Terminated = <<Ex>;>
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{! "\git docs/statix_start:syntax/fostr.sdf3" extract:
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start: TermEx.Terminate
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stop: (.*bracket.*)
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!}
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```
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(The first four clauses are in comments because they approximate fostr's
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grammar; it actually uses a few more sorts for sequences of
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expressions, to achieve fostr's exact layout rules. Also note that the parsing
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of literal strings later evolved to include the surrounding single quotes,
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because the rule above implicitly allows layout between the quotes and the
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string contents, creating ambiguity.)
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This was the first point at which there were two different types that might
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need to be written to standard output (Int and String), and although of course
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the dynamically-typed Python and Javascript code generated dealt with both fine,
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the Haskell code needed to differ depending on the
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type of the item written (and I hadn't even started OCaml code generation at
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that point since I knew it would be hopeless without statically typing fostr
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programs).
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So it was time to bite the bullet and add type checking via Statix to fostr.
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The first step was to replace the simple assertion that any TopLevel
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is OK with a constraint that its Seq must type properly, and an assignment of
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that type to the top level node:
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```statix
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programOk(tl@TopLevel(seq)) :- {T}
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type_Seq(seq) == T,
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@tl.type := T.
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```
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Of course, for this to even parse, we must have a definition of `type_Seq`:
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```statix
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{! ../signature/TYPE.stx extract: {start: module, stop: rules} !}
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**/
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// see docs/implementation.md for detail on how to switch to multi-file analysis
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rules // single-file entry point
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programOk : Start
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programOk(TopLevel(_)).
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/** md
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rules
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type_Seq : Seq -> TYPE
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```
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**/
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type_LineSeq : LineSeq -> TYPE
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programOk(tl@TopLevel(seq)) :- {T}
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type_LineSeq(seq) == T,
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@tl.type := T.
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/** md
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Now to type a Seq, we look to the syntax, and see that there are two
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possibilities for what it might be: just an Ex, or a Sequence(_) of a
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list of 'Ex's. For the first, Statix does not allow one sort to simply
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"become" another, but the Spoofax infrastructure automatically inserts
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"injection" constructors for us, in this case one named Ex2Seq. So the
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first rule for `type_Seq` is straightforward:
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```statix
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type_Seq(s@Ex2Seq(e)) = T : -
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type_Ex(e) == T,
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@s.type := T.
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```
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where of course type_Ex needs its own declaration analogous to the above.
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**/
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type_Line : Line -> TYPE
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type_LineSeq(ls@Line2LineSeq(l)) = T :-
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type_Line(l) == T,
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@ls.type := T.
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/** md
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The other (and in fact more typical) rule for `type_Seq`, when it actually
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consists of a sequence of expressions, is a bit more involved. Fortunately
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Statix provides a primitive for mapping over a list, so we can proceed as
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follows:
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```statix
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types_Exs maps type_Ex(list(*)) = list(*)
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type_Seq(s@Sequence(l)) = T :- {lt}
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types_Exs(l) == lt,
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lastTYPE(lt) == T,
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@s.type := T.
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```
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Here `lastTYPE` is a function that extracts the last TYPE from a list.
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Unless/until Statix develops some sort of standard library, it must be
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hand-defined, as done in "statics/util.stx" like so:
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```statix
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{! ../statics/util.stx extract: {start: lastTYPE} !}
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```
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**/
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types_Lines maps type_Line(list(*)) = list(*)
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type_LineSeq(ls@Sequence(l)) = T :- {lt}
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types_Lines(l) == lt,
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lastTYPE(lt) == T,
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@ls.type := T.
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type_OptTermEx : OptTermEx -> TYPE
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type_Line(l@OptTermEx2Line(ote)) = T :-
|
||||
type_OptTermEx(ote) == T,
|
||||
@l.type := T.
|
||||
|
||||
type_Ex : Ex -> TYPE
|
||||
type_TermEx : TermEx -> TYPE
|
||||
|
||||
type_OptTermEx(ote@Ex2OptTermEx(e)) = T :-
|
||||
type_Ex(e) == T,
|
||||
@ote.type := T.
|
||||
|
||||
type_OptTermEx(ote@TermEx2OptTermEx(te)) = T :-
|
||||
type_TermEx(te) == T,
|
||||
@ote.type := T.
|
||||
|
||||
/** md
|
||||
|
||||
This brings us to the syntax rules for the basic expressions themselves,
|
||||
which comprise almost all of the remaining fostr language constructs.
|
||||
But first a mechanism suggested by Ivo Wilms to avoid repeating the node
|
||||
type annotation in every rule:
|
||||
```statix
|
||||
**/
|
||||
|
||||
/** md */
|
||||
ty_Ex : Ex -> TYPE
|
||||
|
||||
type_Ex(e) = ty@ty_Ex(e) :-
|
||||
@e.type := ty.
|
||||
/* **/
|
||||
|
||||
/** md
|
||||
```
|
||||
At this stage in fostr's development, there was no difference between a
|
||||
terminated and unterminated expression, so the typing rule for that
|
||||
constructor was trivial:
|
||||
```statix
|
||||
ty_Ex(Terminated(e)) = ty_Ex(e).
|
||||
```
|
||||
**/
|
||||
|
||||
type_TermEx(te@Terminate(e)) = T :-
|
||||
type_Ex(e) == T,
|
||||
@te.type := T.
|
||||
|
||||
/** md
|
||||
|
||||
Now typing literals is straightforward:
|
||||
```statix
|
||||
**/
|
||||
|
||||
/** md */
|
||||
ty_Ex(Int(_)) = INT().
|
||||
ty_Ex(LitString(_)) = STRING().
|
||||
ty_Ex(e@Stream()) = STREAM().
|
||||
/* **/
|
||||
|
||||
/** md
|
||||
```
|
||||
|
||||
Finally we get to the binary operators, and here we use the pattern found in
|
||||
recent versions of the
|
||||
"[chicago](https://github.com/MetaBorgCube/statix-sandbox/tree/master/chicago)"
|
||||
example language and in the Fall 2020 TU-Delft class lecture on
|
||||
[Name Binding and Name Resolution](https://tudelft-cs4200-2020.github.io/lectures/2020/09/24/lecture5/).
|
||||
This pattern lets us specify error messages.
|
||||
|
||||
```statix
|
||||
**/
|
||||
|
||||
/** md */
|
||||
ty_Ex(Sum(e1, e2)) = INT() :-
|
||||
type_Ex(e1) == INT() | error $[Expression [e1] not an Int in sum.]@e1,
|
||||
type_Ex(e2) == INT() | error $[Expression [e2] not an Int in sum.]@e2.
|
||||
|
||||
ty_Ex(Gets(e1, e2)) = STREAM() :- {T}
|
||||
type_Ex(e1) == STREAM() | error $[Only Streams may receive items.]@e1,
|
||||
type_Ex(e2) == T.
|
||||
|
||||
ty_Ex(To(e1, e2)) = T :-
|
||||
type_Ex(e1) == T,
|
||||
type_Ex(e2) == STREAM() | error $[Items may only be sent to Streams.]@e2.
|
||||
/* **/
|
||||
|
||||
/** md
|
||||
```
|
||||
|
||||
### Using type annotations in transformation
|
||||
|
||||
At this point, Statix properly types all of the valid programs of the very
|
||||
rudimentary language defined by the grammar above. But the proximate purpose
|
||||
for implementing this typing was to aid Haskell code generation. So how
|
||||
do we actually use the assigned types in a Stratego transformation?
|
||||
|
||||
Statix provides a Stratego api that includes, among other items, strategies
|
||||
`stx-get-ast-analysis` and `stx-get-ast-type(|analysis)` that provide access
|
||||
to the assigned types. However, it's easiest to use the information via
|
||||
a wrapper like this, essentially lifted from the "chicago" language project:
|
||||
```stratego
|
||||
{! analysis.str extract:
|
||||
start: Extract.the.type
|
||||
terminate: Prints.the.analyzed.type
|
||||
!}
|
||||
```
|
||||
|
||||
Now `get_type` run on a node of the analyzed AST produces the assigned `TYPE`
|
||||
(as an ATerm in the constructors of sort TYPE in Statix).
|
||||
|
||||
Thus, you can select on the assigned type, as in the strategy to select
|
||||
the correct Haskell operator to use to send an item to standard output:
|
||||
```stratego
|
||||
{! haskell.str extract:
|
||||
start: '(.*hs_getOp.=.*)'
|
||||
stop: \s
|
||||
!}
|
||||
```
|
||||
**/
|
||||
|
||||
rules // multi-file entry point
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue