Stdlib.Genlex(3)

💖 NAME 💖

Stdlib.Genlex — bestie, there is literally no description here, the manpage just says "no description" and honestly? iconic minimalism. 💅 (It's the OCaml stdlib's general-purpose lexer module, iykyk.)

This page lives in the OCaml library manual. 🦋

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🎀 MODULE 🎀

Module Stdlib.Genlex

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✨ DOCUMENTATION ✨

Module Genlex is a submodule of (module Stdlib__Genlex) — so it's part of the standard library gang, no extra install needed. 🫶

🌈 the token type

type token =
 | Kwd of string
 | Ident of string
 | Int of int
 | Float of float
 | String of string
 | Char of char

okay so this is the type of tokens, periodt. 💀 The lexical classes are literally right here:

• Int and Float — for integer and floating-point numbers 🔢
• String — for string literals, enclosed in double quotes
• Char — for character literals, enclosed in single quotes
• Ident — for identifiers (either sequences of letters, digits, underscores and quotes, or sequences of 'operator characters' such as +, *, etc)
• Kwd — for keywords (either identifiers or single 'special characters' such as (, }, etc)

🧚 make_lexer

val make_lexer : string list -> char Stream.t -> token Stream.t

Construct the lexer function, bestie — this is the main character of the whole module 👑

The first argument is the list of keywords. Here's the tea on how it behaves:

• An identifier s is returned as Kwd s if s belongs to this list, and as Ident s otherwise. ✨
• A special character s is returned as Kwd s if s belongs to this list, and cause a lexical error (exception Stream.Error with the offending lexeme as its parameter) otherwise. 😭 so if you forget to list your special char, boom, error.

Blanks and newlines are skipped. 🌸 Comments delimited by (* and *) are skipped as well, and can be nested — yes bestie, nested, we love a recursive comment situation 🎀

A Stream.Failure exception is raised if end of stream is unexpectedly reached. so watch out for that 💀

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and that's the whole page, no cap. stay slay, lex responsibly 💜

sign-off szn: this was brought to you by OCamldoc, version dated 2026-09-24, serving you Stdlib.Genlex(3) 🎀✨ mwah 💋