Learn OCaml — From Zero to Advanced A structured, hands-on OCaml curriculum with 30 progressive exercises. Each exercise is a self-contained Dune project containing:
README.md — theory explanation + numbered practice assignmentslib/exercise.mlfailwith "not implemented" stubs for you to fill intest/exercise_spec.ml
Prerequisites: opam with OCaml 5.2 and dune
# Install test dependency (once)# Enter an exercisecd exercises/01-hello-ocaml
# Run the tests (they will all fail until you implement the stubs)test
# Open a REPL for the exerciseYour job for each exercise: read README.md, then edit lib/exercise.ml to replace failwith "not implemented" stubs with working implementations until all tests pass.
#
Exercise
Key Concepts
01
hello-ocaml utop, print_endline, Printf.printf, let, string ^
02
types-and-values int, float, bool, char, string, type annotations, conversion fns
03
functions let f x =, fun x ->, partial application, |>, @@
04
pattern-matching match … with, tuple patterns, wildcards, exhaustiveness
05
conditionals if/then/else, match guards (when), nested conditions
06
lists [], ::, List.map/filter/fold_left/fold_right/length/rev
07
recursion base/recursive cases, structural recursion, accumulator pattern
08
higher-order-functions List.map/filter/fold_left, function composition, Fun.compose
09
variants-and-records type t = A | B of …, record types, pattern matching on both
10
modules-and-signatures module M = struct … end, module type S = sig … end, dot notation
Part 2 — Core Abstractions
#
Exercise
Key Concepts
11
option-and-result option, result, Option.map/bind/value, Result.map/bind
12
map-and-set Map.Make, Set.Make (functors), Map.S/Set.S interfaces
13
sequences-and-arrays Array, Seq (lazy), Array.map/fold, Seq.map/filter/take
14
strings-and-buffers String module, Buffer, Bytes, String.split_on_char, Printf.sprintf
15
io-and-refs print_string, read_line, file IO, ref/!/:=
#
Exercise
Key Concepts
16
exceptions exception E of t, raise, try … with, Result vs exceptions
17
mutable-state ref, Array, Hashtbl, Queue, Stack
18
advanced-modules parameterized modules (functors), first-class modules, (module M : S)
19
data-structures Map, Set, Queue, Stack, Hashtbl — pick-the-right-structure problems
20
tail-recursion tail-call pattern, CPS transform, List.rev_append, fold_left vs naive
#
Exercise
Key Concepts
21
polymorphism parametric polymorphism 'a, phantom types, abstract types via signature
22
gadts GADT type _ t = …, existential types, type-safe heterogeneous structures
23
ppx-and-deriving ppx_deriving.show/eq/ord, [@@deriving show, eq], attribute syntax
24
domains-and-concurrency Domain.spawn, Mutex, Semaphore, Atomic, OCaml 5 parallelism
25
algebraic-effects Effect.perform, Effect.Deep.match_with, handler patterns (OCaml 5)
#
Exercise
Key Concepts
26
format-and-pp Format, pp_print_*, %a format spec, structured pretty printing
27
lazy-and-memoization lazy, Lazy.force, memoization with Hashtbl, lazy streams
28
parsing Angstrom: let*, return, string, char, many, choice
29
c-interop external declarations, C stubs, Bigarray, Ctypes basics
30
profiling-optimization landmarks, core_bench, strictness, boxing, allocation avoidance
# Run every exercise's test suitefor dir in exercises/* /; do (cd " $dir " && dune test); done