✨ working example parser

Author: nabeelvalley

README.md

@@ -1,19 +1,36 @@
 # parz
 
-> Learning about Parser Combinators using [The YouTube Series by Low Byte Productions](https://www.youtube.com/playlist?list=PLP29wDx6QmW5yfO1LAgO8kU3aQEj8SIrU)
+A simple parser combinator library
+
+> Trying to learn [Gleam]() while also Learning about Parser Combinators using
+> [The YouTube Series by Low Byte Productions](https://www.youtube.com/playlist?list=PLP29wDx6QmW5yfO1LAgO8kU3aQEj8SIrU)
+> and [Understanding Parser Combinators](https://fsharpforfunandprofit.com/posts/understanding-parser-combinators/)
 
 [![Package Version](https://img.shields.io/hexpm/v/parz)](https://hex.pm/packages/parz)
 [![Hex Docs](https://img.shields.io/badge/hex-docs-ffaff3)](https://hexdocs.pm/parz/)
 
+The project exposes the following modules:
+
+1. `parz.` - contains the `run` method which is used for executing a parser
+2. `parz/combinators` - the parser combinator library
+3. `pars/parsers` - some simple, prmiitive parsers
+
+## Usage
+
 ```sh
 gleam add parz
 ```
 
 ```gleam
-import parz
+import parz.{run}
+import pars/combinators
+import pars/parsers
 
 pub fn main() {
-  // TODO: An example of the project in use
+  // For an example usage look at the `tests/sample_parser_test.gleam` file
+  let parser = // .. define a parser
+
+  let result = run(parser, content_to_parse)
 }
 ```
 

src/parz/combinators.gleam

@@ -1,7 +1,6 @@
 import gleam/list
 import gleam/string
 import parz/types.{type Parser, type ParserState, ParserState}
-import parz/util.{tap}
 
 fn sequence_rec(
   parsers: List(Parser(a)),

src/parz/util.gleam

@@ -0,0 +1,89 @@
+import gleeunit/should
+import parz.{run}
+import parz/combinators.{label_error, left, map, separator1, sequence}
+import parz/parsers.{letters, regex, str}
+import parz/types.{ParserState}
+
+type Kind {
+  StringKind
+  BooleanKind
+  NumberKind
+  UnknownKind
+}
+
+type Identifier {
+  Identifier(name: String)
+}
+
+type Node {
+  UnknownNode
+  Node(name: Identifier, kind: Kind)
+}
+
+type NodePart {
+  K(kind: Kind)
+  I(identifier: Identifier)
+}
+
+type AST {
+  AST(List(Node))
+}
+
+const input = "name:string;
+age:number;
+active:boolean;"
+
+const custom_error = "Expected : but found something else"
+
+fn parser() {
+  let name =
+    left(letters(), str(":") |> label_error(custom_error))
+    |> map(Identifier)
+    |> map(I)
+
+  let kind =
+    left(letters(), str(";"))
+    |> map(fn(ok) {
+      case ok {
+        "string" -> StringKind
+        "number" -> NumberKind
+        "boolean" -> BooleanKind
+        _ -> UnknownKind
+      }
+    })
+    |> map(K)
+
+  let node =
+    sequence([name, kind])
+    |> map(fn(ok) {
+      case ok {
+        [I(i), K(k)] -> Node(i, k)
+        _ -> UnknownNode
+      }
+    })
+
+  let whitespace = regex("\\s*")
+
+  let parser = separator1(node, whitespace) |> map(AST)
+
+  parser
+}
+
+pub fn simple_parser_test() {
+  run(parser(), input)
+  |> should.be_ok
+  |> should.equal(ParserState(
+    AST([
+      Node(Identifier("name"), StringKind),
+      Node(Identifier("age"), NumberKind),
+      Node(Identifier("active"), BooleanKind),
+    ]),
+    "",
+  ))
+}
+
+pub fn simple_parser_error_test() {
+  run(parser(), "name;number")
+  |> should.be_error
+  |> should.equal(custom_error)
+}