Questions tagged [type-inference]

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9
votes
2answers
964 views

Type inference + overloading

I'm looking for a type inference algorithm for a language I'm developing, but I couldn't find one that suits my needs because they usually are either: à la Haskell, with polymorphism but no ad-hoc ...
9
votes
3answers
600 views

Equivalence of data-flow analysis, abstract interpretation and type inference?

@Babou's answer to a recent question reminds me that at one time I think I read a paper about the equivalence (in terms both of the facts that can be inferred or proved and the time complexity of ...
1
vote
2answers
249 views

Program interpretation for static analysis

Are there any implementations, or even academic work, regarding an application capable of looking at code and inferring what the code actually intends to do? For example, we give it a program that ...
5
votes
1answer
291 views

Why injection into sum type apparently leads to ambiguity?

I have been reading Benjamin Pierce's Types and Programming Languages, plus a couple of course notes on type systems and typed $\lambda$-calculus, and there is one thing I don't get: it seems that ...
0
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0answers
398 views

Type inference and Type checking

I understand that adding the annotations (dependent typing) may cause the type checking of the programming language to become undecidable. What about type inference ? Whether type checking and type ...
3
votes
1answer
175 views

Top-down typing strategy - is there a name for this?

In most statically typed languages, each expression has an intrinsic type. E.g. in Java, 3 is an int, 3.0 is a double, ...
3
votes
0answers
736 views

Row polymorphism, union and intersection types

It seems that row polymorphism with union types can be used in dynamic languages to approximate overloading, e.g. given the following python function: ...
4
votes
0answers
187 views

Updating types during type inference in a Hindley-Milner type system

I'm looking at implementing type inference for a Hindley-Milner type system, and before I have even started to implement the Damas-Milner algorithm, while working through some examples, I hit some ...
14
votes
1answer
2k views

Why will the Hindley-Milner algorithm never yield a type like t1 -> t2?

I'm reading about the Hindley-Milner typing algorithm while writing an implementation, and see that, as long as every variable is bound, you'll always get either atomic types or types where the ...
5
votes
1answer
71 views

Is dependency analysis required in order to type a program?

I have seen stated in various places that in order to allow an "increase in polymorphism," functional dependency analysis should be performed, and type inference should be used for every declaration ...
4
votes
1answer
223 views

Meaning of type inference rule for abstraction in lambda-calculus

Below is a snippet about simply typed lambda-calculus from CS152: Programming Languages Lecture 9 | Simply Typed Lambda Calculus, on printed‑page 15, indexed 23. $$ \frac {\Gamma, x: \tau_1 \vdash e: ...
0
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0answers
73 views

Type inference example?

In my programming languages course we are reviewing type inference, i didnt get very well how to make this task. I all ready search at the bibliography of my course (PLAI by Shriram krishnamurthi) ...
10
votes
2answers
2k views

Define a list using only the Hindley-Milner type system

I'm working on a small lambda calculus compiler that has a working Hindley-Milner type inference system and now also supports recursive let's (not in the linked code), which I understand should be ...
3
votes
1answer
163 views

Type inference of pair (product) types

I am looking into Hindler-Milney type system and I am trying to add support for the pair type. In Pierces book, he introduces special language constructs for creation of pairs and getting their ...
0
votes
1answer
207 views

Is constant a variable or subtype?

I think of type as a range of values that the variable can take whereas the rest is known constant or does not matter. Variables (instances or objects), which share common properties, are considered ...
4
votes
3answers
941 views

How can SML infer types like this?

Wikipedia says: fun factorial n = if n = 0 then 1 else n * factorial (n-1) A Standard ML compiler is required to infer the static type int -> int of this ...
3
votes
1answer
339 views

ML - Type Interface

From my recitation class - Can you please explain why does operator $"+"$ signature is $ int \rightarrow (int \rightarrow int)$ ? How does this graph is build ? And what is mean $t=u \...
10
votes
1answer
2k views

Concise example of exponential cost of ML type inference

It was brought to my attention that the cost of type inference in a functional language like OCaml can be very high. The claim is that there is a sequence of expressions such that for each expression ...
11
votes
1answer
514 views

Inferring refinement types

At work I’ve been tasked with inferring some type information about a dynamic language. I rewrite sequences of statements into nested let expressions, like so: <...
3
votes
1answer
288 views

Is the type inference here really complicated?

There's a question on SO asking why in Java the right type doesn't get picked in a concrete case. I know that Java can't do it in such "complicated" cases, but I'm asking myself WHY? The (for ...