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#lang brag
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top : @statement*
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statement : (var | expr | return | defun) /";" | if-else | while
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var : /"var" varname /"=" expr
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@expr : reassignment
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reassignment : ID [("+=" | "-=") expr] | ternary
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ternary : expr /"?" expr /":" expr | logical-or
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logical-or : [logical-or "||"] logical-and
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logical-and : [logical-and "&&"] equal-or-not
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equal-or-not : [equal-or-not ("!=" | "==")] gt-or-lt
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gt-or-lt : [gt-or-lt ("<" | "<=" | ">" | ">=")] add-or-sub
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add-or-sub : [add-or-sub ("+" | "-")] mult-or-div
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mult-or-div : [mult-or-div ("*" | "/")] value
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@value : NUMBER | STRING | object
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| fun | app | increment | varname | /"(" expr /")"
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increment : ("++" | "--") varname | varname ("++" | "--")
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object : /"{" @kvs /"}"
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kvs : [kv (/"," kv)*]
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/kv : expr /":" expr
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defun : /"function" ID /"(" varnames /")" @block
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fun : /"function" /"(" varnames /")" @block
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/varnames : [varname (/"," varname)*]
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@varname : 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 : varname /"(" @exprs /")"
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exprs : [expr (/"," expr)*]
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if-else : /"if" /"(" expr /")" @block ["else" @block]
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while : /"while" /"(" expr /")" @block
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