Validation

PyPScript validation checks whether your .ppc file is structurally sound and internally consistent.

Validation is not about whether the strategy is good.

It is about whether the script is well-formed enough to be trusted as a language document.

Required Structure

Your file should include:

1. header
2. engine line
3. imports for used modules
4. one strategy block
5. one patterns block
6. one default -> HOLD(...) rule
7. one meta block

Minimal valid example:

#!pyp/1.0
engine: pyp-1.0

import indicators.sma
import functions.cross

strategy "valid_minimum" {
    fast_ma = sma.evaluate(close, 10)
    slow_ma = sma.evaluate(close, 20)

    patterns {
        cross(fast_ma, slow_ma) -> UP(confidence: 0.80)
        default -> HOLD(confidence: 0.95)
    }
}

meta {
    author: "PyP"
    version: "1.0.0"
    description: "Minimal valid strategy"
}

Common Validation Failures

Missing Header

Wrong:

engine: pyp-1.0

Fix:

#!pyp/1.0
engine: pyp-1.0

Missing Engine

Wrong:

#!pyp/1.0

Fix:

#!pyp/1.0
engine: pyp-1.0

Missing Import

Wrong:

strategy "broken" {
    trend_ma = sma.evaluate(close, 50)
}

Fix:

import indicators.sma

Missing Default Pattern

Wrong:

patterns {
    trend_up -> UP(confidence: 0.80)
}

Fix:

patterns {
    trend_up -> UP(confidence: 0.80)
    default -> HOLD(confidence: 0.95)
}

Undefined Variable

Wrong:

patterns {
    trend_up and breakout -> UP(confidence: 0.80)
    default -> HOLD(confidence: 0.95)
}

if trend_up or breakout were never defined.

Invalid Confidence

Wrong:

UP(confidence: 1.2)
DOWN(confidence: -0.1)

Confidence should stay in the 0.0 to 1.0 range.

Logical Validation Matters Too

A script can be syntactically valid and still be logically broken.

Examples:

• unreachable patterns
• contradictory conditions
• overly broad first rule
• no realistic hold state

Example of unreachable logic:

patterns {
    above(rsi_value, 50) -> UP(confidence: 0.70)
    above(rsi_value, 80) -> UP(confidence: 0.92)
    default -> HOLD(confidence: 0.95)
}

The second rule is valid syntax, but poor logic.

Validation Checklist

Before you call a script “ready”, check:

• header exists
• engine line exists
• every module used is imported
• variable names are clear and consistent
• every named condition is defined before use
• patterns block exists
• strongest rules are above weaker ones
• default -> HOLD(...) exists
• meta block is present and readable
• config matches the intended pair and timeframe scope

Meta And Config Are Part Of Validation Quality

Even if a script parses, weak metadata still makes it harder to trust.

Weak:

meta {
    author: "me"
    version: "1"
}

Better:

meta {
    author: "PyP"
    version: "1.0.0"
    description: "Trend continuation with momentum confirmation"
}

A Clean Validation Example

#!pyp/1.0
engine: pyp-1.0

import indicators.sma
import indicators.rsi
import functions.above
import functions.below
import functions.cross

strategy "validation_example" {
    fast_ma = sma.evaluate(close, 20)
    slow_ma = sma.evaluate(close, 50)
    rsi_value = rsi.evaluate(close, 14)

    trend_up = above(fast_ma, slow_ma)
    trend_down = below(fast_ma, slow_ma)
    long_trigger = trend_up and above(rsi_value, 55) and cross(close, fast_ma)
    short_trigger = trend_down and below(rsi_value, 45) and cross(fast_ma, close)

    patterns {
        long_trigger -> UP(confidence: 0.84)
        short_trigger -> DOWN(confidence: 0.84)
        default -> HOLD(confidence: 0.96)
    }
}

meta {
    author: "PyP"
    version: "1.0.0"
    description: "Valid trend and momentum example"
}

config {
    pairs: ["EURUSD"]
    timeframes: ["5m"]
}

Validation Goal

A validated script should be:

• parseable
• readable
• internally consistent

That is the standard to aim for before anything else.