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Version: v7.1.0

consult/1

Description​

consult/1 is a predicate which read files as Prolog source code.

Signature​

consult(+Files) is det

where:

  • Files represents the source files to be loaded. It can be an atom or a list of atoms representing the source files.

The Files argument are typically URIs that point to the sources file to be loaded through the Virtual File System (VFS). Please refer to the open/4 predicate for more information about the VFS.

Examples​

Consult a Prolog program​

This scenario demonstrates how to consult (load) a Prolog program from a CosmWasm smart contract.

Assuming the existence of a CosmWasm smart contract configured to store a Prolog program, we construct a URI to specifically identify this smart contract and pinpoint the Prolog program we want to consult via a query message.

Here's the steps of the scenario:

  • Given the CosmWasm smart contract "okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht" and the behavior:
message: |
  {
    "object_data": {
      "id": "4cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05"
    }
  }
response: |
  hello("World!").
  • Given the program:
:-
  uri_encoded(query_value, '{"object_data":{"id": "4cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05"}}', Query),
  atom_concat('cosmwasm:storage:okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht?base64Decode=false&query=', Query, URI),
  consult(URI).
  • Given the query:
hello(Who).
  • When the query is run
  • Then the answer we get is:
height: 42
gas_used: 2224
answer:
  has_more: false
  variables: ["Who"]
  results:
  - substitutions:
    - variable: Who
      expression: "['W',o,r,l,d,!]"

Consult a Prolog program which also consults another Prolog program​

This scenario demonstrates the capability of a Prolog program to consult another Prolog program. This is useful for modularizing Prolog programs and reusing code.

Note that the :- multifile/1 directive is employed to enable a single predicate's definition to span several files. In the absence of this directive, encountering a new definition would lead the compiler to overwrite the existing predicate definition.

Here's the steps of the scenario:

  • Given the CosmWasm smart contract "okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht" and the behavior:
message: |
  {
    "object_data": {
      "id": "4cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05"
    }
  }
response: |
  :- multifile(program/1).
  :- consult('cosmwasm:storage:okp412ssv28mzr02jffvy4x39akrpky9ykfafzyjzmvgsqqdw78yjevpqgmqnmk?query=%7B%22object_data%22%3A%7B%22id%22%3A%20%225d3933430d0a12794fae719e0db87b6ec5f549b2%22%7D%7D&base64Decode=false').

  program(a).
  • Given the CosmWasm smart contract "okp412ssv28mzr02jffvy4x39akrpky9ykfafzyjzmvgsqqdw78yjevpqgmqnmk" and the behavior:
message: |
  {
    "object_data": {
      "id": "5d3933430d0a12794fae719e0db87b6ec5f549b2"
    }
  }
response: |
  :- multifile(program/1).

  program(b).
  • Given the query:
  consult('cosmwasm:storage:okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht?query=%7B%22object_data%22%3A%7B%22id%22%3A%20%224cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05%22%7D%7D&base64Decode=false'),
  program(X).
  • When the query is run (limited to 2 solutions)
  • Then the answer we get is:
height: 42
gas_used: 2223
answer:
  has_more: false
  variables: ["X"]
  results:
  - substitutions:
    - variable: X
      expression: "b"
  - substitutions:
    - variable: X
      expression: "a"

Consult several Prolog programs​

This scenario demonstrates the consultation of several Prolog programs from different CosmWasm smart contracts.

Here's the steps of the scenario:

  • Given the CosmWasm smart contract "okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht" and the behavior:
message: |
  {
    "object_data": {
      "id": "4cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05"
    }
  }
response: |
  program(a).
  • Given the CosmWasm smart contract "okp412ssv28mzr02jffvy4x39akrpky9ykfafzyjzmvgsqqdw78yjevpqgmqnmk" and the behavior:
message: |
  {
    "object_data": {
      "id": "5d3933430d0a12794fae719e0db87b6ec5f549b2"
    }
  }
response: |
  program(b).
  • Given the program:
  :- consult([
    'cosmwasm:storage:okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht?query=%7B%22object_data%22%3A%7B%22id%22%3A%20%224cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05%22%7D%7D&base64Decode=false',
    'cosmwasm:storage:okp412ssv28mzr02jffvy4x39akrpky9ykfafzyjzmvgsqqdw78yjevpqgmqnmk?query=%7B%22object_data%22%3A%7B%22id%22%3A%20%225d3933430d0a12794fae719e0db87b6ec5f549b2%22%7D%7D&base64Decode=false'
   ]).
  • Given the query:
source_file(File).
  • When the query is run (limited to 2 solutions)
  • Then the answer we get is:
height: 42
gas_used: 2223
answer:
  has_more: false
  variables: ["File"]
  results:
  - substitutions:
    - variable: File
      expression: "'cosmwasm:storage:okp412ssv28mzr02jffvy4x39akrpky9ykfafzyjzmvgsqqdw78yjevpqgmqnmk?query=%7B%22object_data%22%3A%7B%22id%22%3A%20%225d3933430d0a12794fae719e0db87b6ec5f549b2%22%7D%7D&base64Decode=false'"
  - substitutions:
    - variable: File
      expression: "'cosmwasm:storage:okp415ekvz3qdter33mdnk98v8whv5qdr53yusksnfgc08xd26fpdn3ts8gddht?query=%7B%22object_data%22%3A%7B%22id%22%3A%20%224cbe36399aabfcc7158ee7a66cbfffa525bb0ceab33d1ff2cff08759fe0a9b05%22%7D%7D&base64Decode=false'"