Thoth.Parser

Common commit parser library used by other EasyBuild tools like EasyBuild.ChangelogGen or EasyBuild.CommitLinter.

Thoth.Parser is a parsing library aiming to provide a simple and efficient way to parse text.

It aims to be:

• Terse: The syntax should be as simple as possible

• Speedy: Go fast enough for most use cases

• Modular: Allow for easy extension and modification

• Cross-platform:

  Thanks to Fable, Thoth.Parser can be used on different runtime

  • .NET ✅
  • JavaScript 🚧 (planned)
  • Python 🚧 (planned)

⚠️ Thoth.Parser is in early development and the API is subject to change.

openThoth.ParseropenThoth.Parser.OperatorstypePoint={
X:int
Y:int}modulePoint =letparser=
Parser.succeed (fun x y ->{
X = x
Y = y
})|. Parser.token "("|. Parser.spaces
|= Parser.int32
|. Parser.spaces
|. Parser.token ","|. Parser.spaces
|= Parser.int32
|. Parser.spaces
|. Parser.token ")"|. Parser.exhausted

Installation

You can install Thoth.Parser via NuGet:

dotnet add package Thoth.Parser

Usage

Pipeline VS Operators

Thoth.Parser provides two syntaxes:

• The pipeline syntax

  • Parser.drop to ignore the result of a parser
  • Parser.keep to keep the result of a parser

• The operator syntax

  • |. equivalent to Parser.drop
  • |= equivalent to Parser.keep

Pipeline example

openThoth.Parser
Parser.succeed (fun x y ->{
X = x
Y = y
})|> Parser.drop (Parser.token "(")|> Parser.drop Parser.spaces
|> Parser.keep Parser.int32
|> Parser.drop Parser.spaces
|> Parser.drop (Parser.token ",")|> Parser.drop Parser.spaces
|> Parser.keep Parser.int32
|> Parser.drop Parser.spaces
|> Parser.drop (Parser.token ")")|> Parser.drop Parser.exhausted

As you can see, thanks to drop and keep, being short and 4 characters long, the code is aligned and easy to read.

Tip

To make sure the code is aligned, it is recommended to use a monospaced font.

Operators example

openThoth.ParseropenThoth.Parser.Operators
Parser.succeed (fun x y ->{
X = x
Y = y
})|. Parser.token "("|. Parser.spaces
|= Parser.int32
|. Parser.spaces
|. Parser.token ","|. Parser.spaces
|= Parser.int32
|. Parser.spaces
|. Parser.token ")"|. Parser.exhausted

If you are using Fantomas to format your F# code, it can happens that Fantomas will format the code in a single line.

letnumber=
Parser.succeed Number.Create
|= Parser.sign
|= Parser.int32
// will be formatted asletnumber=
Parser.succeed Number.Create |= Parser.sign |= Parser.int32

To prevent this, you can use fsharp_max_infix_operator_expression setting to minimize the chance of this happening.

Another solution is to add comments between the operators.

letnumber=
Parser.succeed Number.Create
//|= Parser.sign
//|= Parser.int32