52 lines
1.5 KiB
Plaintext
52 lines
1.5 KiB
Plaintext
module haskell
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imports libstrategolib signatures/- util
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signature
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constructors
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TopLevel: Ex -> Ex
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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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*/
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hs: TopLevel((c,p)) -> $[import System.IO
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data IOStream = StdIO
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stdio :: IO IOStream
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stdio = return StdIO
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receives :: Show b => IO a -> b -> IO a
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receives s d = do
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temp <- s
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putStr(show d)
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return temp
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main = do
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[p]return [c]]
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hs: Stdio() -> ("stdio", "")
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hs: Int(x) -> (x, "")
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hs: Sum((c,p)) -> ($[sum [c]], p)
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hs: Receives((c, p), (d, s)) -> ($[[c] `receives` [d]], <conc-strings>(p,s))
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hs: Enters((c, p), (d, s)) -> <hsenter>(c,d,<conc-strings>(p,s),<newname>"fos")
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hsenter: (x, s, p, v) -> (v, <concat-strings>[$[[p]let [v] = [x]], "\n",
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$[[s] `receives` [v]], "\n"])
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hslist: x -> (<map(Fst); join(|", "); brack>x, <map(Snd); concat-strings>x)
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brack: x -> $<[<x>]>
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strategies
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// wrap expression in a toplevel and then apply code generation
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haskell = !TopLevel(<id>); bottomup(try(hs <+ hslist))
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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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with filename := <guarantee-extension(|"hs")> path
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; result := <haskell> selected
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