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24 lines
665 B
Racket
24 lines
665 B
Racket
5 years ago
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#lang brag
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top : @statement*
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statement : (var | expr | return) /";" | if | while
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var : /"var" id /"=" expr
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@expr : comparison
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comparison : [comparison ("!=" | "==")] add-or-sub
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add-or-sub : [@add-or-sub /"+"] value
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@value : id | INTEGER | STRING | object
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| fun | app | increment
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increment : id /"++"
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object : /"{" @kvs /"}"
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kvs : [kv (/"," kv)*]
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/kv : expr /":" expr
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fun : /"function" /"(" ids /")" @block
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/ids : [id (/"," id)*]
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@id : ID | deref
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deref : DEREF
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block : /"{" @statement* /"}"
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return : /"return" expr
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app : id /"(" @exprs /")"
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exprs : [expr (/"," expr)*]
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if : /"if" /"(" expr /")" @block ["else" @block]
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while : /"while" /"(" expr /")" @block
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