小编anp*_*npv的帖子

使用直接外部函数的版本(calc1)大约需要1秒.

但是带有传递函数作为函数参数的版本(calc2)大约需要2s,即慢2倍.为什么？

open System.Diagnostics
open System.Numerics

let width = 1920
let height = 1200
let xMin = -2.0
let xMax = 1.0
let yMin = -1.0
let yMax = 1.0
let scaleX x = float x * (xMax - xMin) / float width + xMin
let scaleY y = float y * (yMax - yMin) / float height - yMax

let fn (z:Complex) (c:Complex) = z * z + c

let calc1 width height =
    let iterFn z c = …

我正在为类似于SQL的语言开发解析器,我遇到了创建一些语言规则的问题,例如:expression IS NULL和expression IN (expression1, expression2, ...)逻辑和数学运算符之间的优先级.

我上传了一个GitHub测试项目https://github.com/anpv/SpracheTest/,但这个变种并不好.
我试图使用以下规则:

private static readonly Parser<AstNode> InOperator =
    from expr in Parse.Ref(() => Expression)
    from inKeyword in Parse.IgnoreCase("in").Token()
    from values in Parse
        .Ref(() => Expression)
        .DelimitedBy(Comma)
        .Contained(OpenParenthesis, CloseParenthesis)
    select new InOperator(expr, values);

private static readonly Parser<AstNode> IsNullOperator =
    from expr in Parse.Ref(() => Expression)
    from isNullKeyword in Parse
         .IgnoreCase("is")
         .Then(_ => Parse.WhiteSpace.AtLeastOnce())
         .Then(_ => Parse.IgnoreCase("null"))
    select new IsNullOperator(expr);

private static readonly Parser<AstNode> Equality =
    Parse
        .ChainOperator(Eq, IsNullOperator.Or(InOperator).Or(Additive), …