Add the Lexa language #64
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@jasigal Hi Jesse, can you review this PR? |
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Will do later this week! |
jasigal
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Looks great, just some small changes suggested to be consistent with the other implementations, and some questions about Lexa.
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| def set(i) { | ||
| s[0] := i; | ||
| 0 |
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Question: Why does this return 0 instead of the unit value?
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| type generator = | ||
| | Empty | ||
| | Thunk of int * (cont <> unit -> generator) |
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Change: The other implementations appear to store functions here instead of continuations. I think to maintain consistency the same should be done here.
| def generate(f: <> [; yield_stub: Yield] () -> int): generator { | ||
| handle <> { | ||
| f:[; yield_stub](); | ||
| Empty() |
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Nit: Does Lexa have return clauses? It would be nice to maintain consistency if it does.
| Empty() | ||
| } with yield_stub: Yield { | ||
| hdl_1 yield(x, k) { | ||
| Thunk(x, k) |
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See above comment about storing functions versus continuations.
| match g with | ||
| | Empty -> { a } | ||
| | Thunk (v, f) -> { | ||
| sum(v + a, resume_final f (())) |
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See above comment about storing functions versus continuations.
| @@ -0,0 +1,56 @@ | |||
| effect Search { | |||
| pick: (int) -> int | |||
| fail: () -> int | |||
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Technically the return type of fail is prescribed to be void/empty. Does Lexa have this?
| parse:[;read_stub, emit_stub, stop_stub](0) | ||
| } | ||
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| def sum_action [;emit_stub: Emit] (n: int): int { |
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Would you mind explaining what's going on here? Are the functions being passed by reference?
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| effect Choice { | |||
| flip: () -> int | |||
| fail: () -> int | |||
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Same question about void/empty.
| val j = choice:[; choice_stub](i - 1); | ||
| val k = choice:[; choice_stub](j - 1); | ||
| if i + j + k == s then | ||
| hash(i, j, k) |
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Question: Does Lexa have tuples? If so, hash should be moved to run to maintain consistency.
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| def run(n: int, s: int): int { | ||
| handle <> { | ||
| triple:[; choice_stub](n, s) |
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See above, hash would be here.
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Thanks Jesse, these are very useful comments! Some need modification to the Lexa compiler itself, and I'll resolve them next week. |
This PR adds the Lexa language.
https://github.com/lexa-lang/lexa