F#使用地图解密类型 [英] F# Deciphering a type with maps

问题描述

我只是从F#开始，我想知道如何从书籍示例中解读以下类型及其代表的含义:

I'm just starting out in F# and I'm wondering how to decipher the following types and what they represent from a book example:

type subs = Map<string,exp> option

type lp = (subs->subs) ->subs->subs // A LP computation

我知道子类型只是带有字符串和关联的exp类型的映射...但是我不理解'->'的使用以及lp类型的赋值是什么...

I understand the sub type is simply a map with strings and an associated exp type... but I dont understand the use of '->' and what the lp type is assigning...

任何解密lp类型的帮助都很好

Any help on deciphering the lp type would be great

推荐答案

->表示一个函数.例如，string -> int表示一个函数，该函数将字符串作为参数，并返回一个整数.

The -> represents a function. For example, string -> int represents a function that takes a string as an argument, and returns an integer.

如果链接->，则从右到左读取:a -> b -> c -> d是a -> (b -> (c -> d)).

If you chain the ->, you read it from right to left: a -> b -> c -> d is a -> (b -> (c -> d)).

函数可以将函数作为参数，因此lp是(subs -> subs) -> subs -> subs，也写为(subs -> subs) -> (subs -> subs).它是一个具有功能的功能. 如果令人困惑，请尝试将其视为fn -> (subs -> subs)，其中type fn = subs -> subs是函数的类型.

Functions can take functions as arguments, so, lp is (subs -> subs) -> subs -> subs, which is also written as (subs -> subs) -> (subs -> subs). It is a function that takes a function. If it is confusing, try to see it as fn -> (subs -> subs), where type fn = subs -> subs, a type for a function.

另请参见: http://en.wikipedia.org/wiki/Higher-order_function

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