public static JymlType[] ParametersToArguments(this Cons cons, Jyml.Environment.JymlEnvironment env)
{
JymlType[] arr = new JymlType[cons.Length];
int i = 0;
foreach (var item in cons)
{
try {
if (item is string str)
{
arr[i] = JymlType.CreateType(str);
}
else if (item is JymlType jymlType)
{
arr[i] = jymlType;
}
else
{
arr[i] = JymlType.CreateType(item);
}
}
catch (InvalidCastException) {
arr[i] = env.GetVariableValue(item as string);
}
i++;
}
return(arr);
}
/*
* ;; eval-assignment 调用 eval 找出需要赋的值，将变量和得到的值传给过程 set-variable-value!，
* ;; 将有关的值安置到指定环境里
* (define (eval-assignment exp env)
* (set-variable-value! (assignment-variable exp)
* (eval (assignment-value exp) env)
* env)
* 'ok)
*/
private static JymlAST.Cons EvalAssignment(JymlAST.Cons exp, JymlEnvironment env)
{
env.SetVariableValue(
var: (exp.cdr as JymlAST.Cons).car as string,
val: JymlType.CreateType(((exp.cdr as JymlAST.Cons).cdr as JymlAST.Cons).car as string)
);
return(null);
}
public void AddBindingToFrame(string var, JymlType val)
{
if (this[var] == null)
{
this.Restraints.AddFirst(new Restraint(var, val));
}
else
{
throw new Exception($"变量 {var} 重定义。");
}
}
/*
* (define (eval-definition exp env)
* (define-variable! (definition-variable exp)
* (eval (definition-value exp) env)
* env))
*/
private static JymlAST.Cons EvalDefinition(JymlAST.Cons exp, JymlEnvironment env)
{
/*
* (define (definition-variable exp)
* (if [symbol? [mcar [mcdr exp]]]
* [mcar [mcdr exp]]
* [mcar [mcar [mcdr exp]]]))
*/
string defineVariable(JymlAST.Cons c) =>
Parser.IsVariable(c.cdr as JymlAST.Cons) ? (c.cdr as JymlAST.Cons).car as string // 普通变量或 lambda 变量
: ((c.cdr as JymlAST.Cons).car as JymlAST.Cons).car as string; // 过程定义
/*
* (define (definition-value exp)
* (if [symbol? [mcar [mcdr exp]]]
* [mcar [mcdr [mcdr exp]]]
* (make-lambda [mcdr [mcar [mcdr exp]]] ; formal parameters
* [mcdr [mcdr exp]]))) ; body
*/
JymlType defineValue(JymlAST.Cons c)
{
if (Parser.IsVariable(c.cdr as JymlAST.Cons))
{
if (((c.cdr as JymlAST.Cons).cdr as JymlAST.Cons).car is string atom)
{
return(JymlType.CreateType(atom)); // 普通变量或 lambda 变量
}
else if (((c.cdr as JymlAST.Cons).cdr as JymlAST.Cons).car is JymlAST.Cons cons)
{
return(JymlType.CreateType(Eval(cons, env).car)); // 返回一个 value 的子表达式（过程调用）
}
else
{
throw new Exception($"define 表达式 {exp} 的 value 部分只能是一个原子值或一个返回原子值的过程调用。");
}
}
else
{
return(new Procedures(Parser.GetProcedureName(exp), (JymlAST.Cons)Parser.GetLambdaParameters(exp), Parser.GetLambdaBody(exp), env)); // 过程定义
}
}
env.DefineVariable(defineVariable(exp), defineValue(exp));
return(null);
}
public Restraint(string var, JymlType val)
{
Variable = var;
Value = val;
}