mirror of
https://github.com/kanaka/mal.git
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03b6cfd45c
Neither keywords nor strings are modified by evaluation, so evaluating map keys is a no-op. Document this in the guide.
52 lines
1.1 KiB
Io
52 lines
1.1 KiB
Io
MalTypes
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MalReader
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READ := method(str, MalReader read_str(str))
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eval_ast := method(ast, env,
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(ast type) switch(
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"MalSymbol", env at(ast val) ifNil(Exception raise("'" .. (ast val) "' not found")),
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"MalList", MalList with(ast map(a, EVAL(a, env))),
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"MalVector", MalVector with(ast map(a, EVAL(a, env))),
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"MalMap",
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m := MalMap clone
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ast foreach(k, v,
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m atPut(k, EVAL(v, env))
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)
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m,
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ast
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)
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)
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EVAL := method(ast, env,
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if(ast type != "MalList", return(eval_ast(ast, env)))
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if(ast isEmpty, return ast)
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el := eval_ast(ast, env)
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f := el at(0)
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args := el rest
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f callWithArgList(args)
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)
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PRINT := method(exp, exp malPrint(true))
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repl_env := Map with(
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"+", block(a, b, a + b),
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"-", block(a, b, a - b),
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"*", block(a, b, a * b),
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"/", block(a, b, a / b)
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)
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RE := method(str, EVAL(READ(str), repl_env))
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REP := method(str, PRINT(RE(str)))
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loop(
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line := MalReadline readLine("user> ")
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if(line isNil, break)
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if(line isEmpty, continue)
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e := try(REP(line) println)
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e catch(Exception,
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("Error: " .. (e error)) println
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)
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)
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