Triceratypes

Practice ML-style type inference step by step
Work in progress - bugs or suggestions? sfreund@williams.edu

Expression Syntax

fn x => e lambda f x application let x = e1 in e2 let binding if c then t else e conditional (e1, e2) tuple + - * < > operators nil empty list x :: xs cons

Declarations

fun f x = e; function def

fun f 0 = e1
  | f n = e2;

pattern match

Constraint Syntax

t1 = int integer type t1 = bool boolean type t1 = t2 -> t3 function type t1 = t2 * t3 tuple type t1 = t2 list list type

Unification Rules

Decompose:

A→B = C→D ⟹ A=C, B=D

A*B = C*D ⟹ A=C, B=D

A list = B list ⟹ A=B

Eliminate:

x=A, C=D ⟹ [A/x]C = [A/x]D

Enter an expression below or start with an example:

more examples

ML Program:

Parse Trees with Type Variables

Phase 1: Generate Constraints

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