Friday , May 7 2021

ltcmelo / psychec, Hacker News



PsycheC is a compiler frontend infrastructure for the C language that is enabled with an ML / Haskell-style (unification-based) type inference engine.This online interfaceillustrates the essential functionality of PsycheC.


  • Cmake
  • C 14 compiler
  • Haskell Stack
  • Python 3

cmake CMakeLists.txt make

Running the Tests

./ psychecgen -t ./ cd solver && stack test

Cnippetcompiler adapter. Let us see an example. *******

Consider the filenode.cBelow.

//node.cvoid(f)  () {     T v=0;     v ->value=42;     v ->next=v; }

If you were to compilenode.cwith GCC / Clang, you would issue a command similar to this one:

gcc -c node. c

As a result, an object filenode.owould have been produced. However, this will not happen, since a declaration forTis not available. Instead, you will get an “undeclared identifier” error.

Now, if you invoke Cnippet, the compilation succeeds (flag- fis for non-commercial use).

./ -f gcc -c node.c

That is because, under the hood, PsycheC will infer the necessary missing definitions.

typedefstructTYPE_1__ {     intvalue;     structTYPE_1 __ * next; } * T;

This is a work-in-progress, feedback is welcome throughthis form.

PsycheC provides an alternative tovoid *and# macrosfor writing generic code in C. This is how you would implement a generic linked-list’sprependfunction.

_ GenericvoidPrepend(_ Forall (node_t) ** head,                       _Forall (value_t) value) {     node_t* n=malloc( (sizeof)  (node_t));     n ->value=value;     n ->next=* head;     * head=n; }

It is not necessary to define neithernode_tnorvalue_t. The definition ofprependapplies “for all” kinds of nodes and values. This way, you can focus on thealgorithms(the essence of generic programming).

Let us create 2 lists, one ofintand another ofpoint_t, and insert an new head to them.

int(main)  () {     _ Exists(node_t) * ilst=(0) ;     Prepend(& ilst,42);      _ Exists(node_t) * plst=(0) ;     struct(point_tp;     P.x=p.y=42;     Prepend(& plst, p); }

Now, PsycheC infers that there “exists” a (node) type whose value is anint, together with an specialization ofprependfor such arguments. A different (node) type forpoint_t“exists” too, with its corresponding specialization ofprepend.

Check the examples directory forthis snippet.


PsycheC is an ongoing research project. It has been presented at:

Below is a list of papers whose developed tooling rely on PsycheC:

This is an online article about PsycheC:


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