OCaml Basics

Work on this exercise locally

This web app is a reference guide — you can read instructions, browse starter code, and view tests here. To actually complete the exercise, you need to work in your local development environment.

1Clone the repo: git clone https://github.com/weihaoqu/program-analysis-bootcamp-student

2Edit the starter file in your editor (VS Code, Vim, etc.) — replace failwith "TODO" with your implementation.

3Run the tests: dune runtest modules/module0-warmup/exercises/ocaml-basics

3. Exercise 1: OCaml Basics (~20 min)

File: exercises/ocaml-basics/starter/main.ml Run:

dune exec modules/module0-warmup/exercises/ocaml-basics/starter/main.exe

What You'll Implement

Function	What It Does	Concept
`square`	Returns x * x	Basic function
`is_empty`	Checks if string is empty	String.length
`greet`	Returns "Hello, name!"	String concatenation
`is_digit`	Checks if char is '0'..'9'	Char comparison
`is_alpha`	Checks if char is letter/underscore	Multiple ranges
`classify_char`	Returns "digit"/"alpha"/"operator"/"unknown"	Using helper functions
`format_token`	Formats a (category, text) tuple	Tuple destructuring
`make_token`	Creates token from text string	String indexing
`format_pos`	Formats a (line, col) position	Printf.sprintf
`advance_pos`	Updates position after reading a char	Newline handling

Hints

String.length s returns the length of s.
s.[0] returns the first character of string s.
Printf.sprintf "line %d, col %d" line col creates a formatted string.
Characters can be compared with <=: '0' <= c && c <= '9'.

Expected Output

=== Exercise 1: OCaml Basics ===

square 5 = 25
square (-3) = 9
is_empty "" = true
is_empty "hi" = false
greet "OCaml" = Hello, OCaml!

classify_char '7' = digit
classify_char 'x' = alpha
classify_char '+' = operator
classify_char '!' = unknown

format_token ("keyword", "if") = [keyword: if]
make_token "42" = [number: 42]
make_token "hello" = [identifier: hello]
make_token "+" = [symbol: +]
make_token "" = [empty: ]

format_pos (1, 1) = line 1, col 1
advance_pos (1,1) 'a' = line 1, col 2
advance_pos (1,3) '\n' = line 2, col 1
scan_positions "ab\ncd" = line 2, col 3

Done!

Starter Files

starter

starter/main.ml

Read-only

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