2021-01-30 20:27:10 +00:00
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module fostr
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imports
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Common
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context-free start-symbols
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2021-02-01 08:29:00 +00:00
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Start
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2021-01-30 20:27:10 +00:00
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context-free sorts
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2021-02-06 05:11:41 +00:00
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Start LineSeq Line Ex
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2021-01-30 20:27:10 +00:00
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context-free syntax
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2021-02-06 05:11:41 +00:00
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Start.TopLevel = LineSeq
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LineSeq = <<ln:Ex>> {layout(offside ln)}
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LineSeq.Sequence = sq:Ex+ {layout(align-list sq)}
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Ex+ = Ex+ ln:Ex {layout(offside ln)}
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2021-02-01 08:29:00 +00:00
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2021-01-30 23:37:53 +00:00
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Ex.Int = INT
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2021-02-06 05:11:41 +00:00
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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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2021-02-01 01:46:31 +00:00
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Ex = <(<Ex>)> {bracket}
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2021-01-30 23:37:53 +00:00
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context-free priorities
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2021-02-06 05:11:41 +00:00
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Ex.To
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2021-02-01 01:46:31 +00:00
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> Ex.Sum
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2021-02-06 05:11:41 +00:00
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> Ex.Gets,
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2021-01-30 23:37:53 +00:00
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// prevent cycle: no singletons
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2021-02-06 05:11:41 +00:00
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LineSeq.Sequence <0> .> Ex+ = Ex,
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2021-01-30 23:37:53 +00:00
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2021-02-06 05:11:41 +00:00
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// flat: No LineSeq immediately in LineSeq
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Ex+ = Ex <0> .> LineSeq.Sequence,
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Ex+ = Ex+ Ex <1> .> LineSeq.Sequence
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