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Questions tagged [evaluator]

59 questions
7
votes
3 answers

In the SECD Machine how does "rap" work?

I am writing a simulator of the SECD machine in C# guided by the description on Wikipedia. I have the basic operations completed, but I am not sure how to implement the rap instruction. At Wikipedia it says about rap: rap works like ap, only that…
cdiggins
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4
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1 answer

How to write a custom evaluator for Share in Alfresco 4.2.2?

For example, I need the evaluator, which I could use to show the action in Share. If the current user is the author of the document, then I'll show the action. The project structure is presented below…
user1134181
4
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1 answer

Attempting to call unbound fn, while I have defined it

I am trying to convert SICP's meta-circular evaluator to Clojure. In setup-environment a call to extend-environment does not compile because I get the error "Attempting to call unbound fn". Here's part of the code: (... loads of methods for creating…
user2609980
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3
votes
1 answer

Evaluating "true" in meta-circular evaluator in Clojure

I converted the Structure and Interpretation of Computer Programs (SICP) version of the meta-circular evaluator to Clojure. The main difference (besides syntax) is the handling of the environment structure. Since you cannot use set-car! and set-cdr!…
user2609980
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3
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1 answer

A Haskell Mini-Language

I'm attempting to define an evaluator for the language E and to be quite frank I'm completely at a loss for how to fix all the errors I keep getting with how the eval type is defined. I've spent several hours now reading up on interpreters, monads…
JustKeepSwimming
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3
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6 answers

Need Help Understanding Recursive Prefix Evaluator

This is a piece of code I found in my textbook for using recursion to evaluate prefix expressions. I'm having trouble understanding this code and the process in which it goes through. char *a; int i; int eval() { int x = 0; …
user3421510
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1 answer

OpenGL 2D Evaluator Mesh cannot set larger

I have this OpenGL project I'm working on that involves creating a 2D flat mesh to mess around with. The code is as such: #include #include GLfloat ctrlpoints[9][9][3] = { {{0, 0, 0}, {1, 0, 0}, {2, 0, 0}, {3, 0, 0}, {4, 0,…
user1858045
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2 answers

Can I run Lua interpreter in evaluator mode?

Many of script interpreters like irb or node works as evaluator. If I execute this code, 10 it will evaluate and print the value itself, and make no error. When I installed lua it worked as executor rather than evaluator. So when I put 10, it will…
eonil
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2
votes
1 answer

Adding params to Apache Spark's abstract Evaluator class

I'm building a Spark Application and am using the Evaluator class within some custom Estimators/Transformers. I've run into an issue where the Evaluator base class does not implement the metricName param that most (all?) of its descendants…
Derek Kaknes
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2
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3 answers

Mutually recursive evaluator in Haskell

Update: I've added an answer that describes my final solution (hint: the single Expr data type wasn't sufficient). I'm writing an evaluator for a little expression language, but I'm stuck on the LetRec construct. This is the language: type Var =…
Tom Lokhorst
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2
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5 answers

How to allow users to define financial formulas in a C# app

I need to allow my users to be able to define formulas which will calculate values based on data. For example //Example 1 return GetMonetaryAmountFromDatabase("Amount due") * 1.2; //Example 2 return GetMonetaryAmountFromDatabase("Amount due") *…
Peter Morris
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2
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2 answers

Metacircular evaluator of Scheme in Dr. Racket

When I am trying to run an evaluator in Dr. Racket, it shows the error: 'Module Language: there can only be one expression in the definitions window'. Obviously there are multiple definitions in this window, an evaluator has multiple definitions,…
Hari Chaudhary
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2
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3 answers

Neo4j Using a custom evaluator to get the depth a node was retrieved at

I'm using the latest version of Neo4j to build up a graph of nodes and relationships with the Java API. My problem is that I need to traverse the nodes to a certain depth. There may exist a relationship between two nodes at the same depth in the…
jenny_flynn
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2
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2 answers

Mule 3.2. How to Evaluate Empty Session Variable in Flow?

How can I check if my session variable is null or empty in this CHOICE Its not working for me. …
Kawika
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1
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1 answer

How can I pass a set of instances to a function or predicate in Alloy Analyzer's Evaluator?

BLUF: I have a predicate which takes as arguments an instance of a signature and a set of instances of the same signature. Upon generating instances of the model, I'd like to pass instances of the signature to the predicate, but am at a loss for how…
JustAnotherSystemsEngineer
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