Context (env+def)

Information about the context of script execution is available in the env global object.

Environment (env)

The env global object contains properties that provide information about the script execution context. env is populated automatically by the GenAIScript runtime.

env.files

The env.files array contains all files within the execution context. The context is defined implicitly by the user based on:

• script files option

script({
    files: "**/*.pdf",
})

or multiple paths

script({
    files: ["src/*.pdf", "other/*.pdf"],
})

• the UI location to start the tool

• CLI files arguments.

The files are stored in env.files which can be injected in the prompt.

• using def

def("FILE", env.files)

• filtered,

def("DOCS", env.files, { endsWith: ".md" })
def("CODE", env.files, { endsWith: ".py" })

• directly in a $ call

$`Summarize ${env.files}.

In this case, the prompt is automatically expanded with a def call and the value of env.files.

// expanded
const files = def("FILES", env.files, { ignoreEmpty: true })
$`Summarize ${files}.

env.vars

The vars property contains the variables that have been defined in the script execution context.

// grab locale from variable or default to en-US
const locale = env.vars.locale || "en-US"

Read more about variables.

Definition (def)

The def("FILE", file) function is a shorthand for generating a fenced variable output. The “meta-variable” (FILE in this example) name should be all uppercase (but can include

def("FILE", file)

approximately equivalent to:

$`FILE ${file.filename}:
```
${env.file.content}
```

The def function can also be used with an array of files, such as env.files.

def("FILE", env.files)

Language

You can specify the language of the text contained in def. This can help GenAIScript optimize the rendering of the text.

// hint that the output is a diff
def("DIFF", gitdiff, { language: "diff" })

Referencing

The def function returns a variable name that can be used in the prompt. The name might be formatted differently to accommodate the model’s preference.

const f = def("FILE", file)

$`Summarize ${f}.`

File filters

Since a script may be executed on a full folder, it is often useful to filter the files based on

• their extension

def("FILE", env.files, { endsWith: ".md" })

• or using a glob:

def("FILE", files, { glob: "**/*.{md,mdx}" })

Tip

You can open the completion menu and discover all the options by pressing Ctrl+Space after the curly brace { character.

def("FILE", env.files, { // press Ctrl+Space

Empty files

By default, if def is used with an empty array of files, it will cancel the prompt. You can override this behavior by setting ignoreEmpty to true.

def("FILE", env.files, { endsWith: ".md", ignoreEmpty: true })

maxTokens

It is possible to limit the number of tokens that are generated by the def function. This can be useful when the output is too large and the model has a token limit. The maxTokens option can be set to a number to limit the number of tokens generated for each individual file.

def("FILE", env.files, { maxTokens: 100 })

Data filters

The def function treats data files such as CSV and XLSX specially. It will automatically convert the data into a markdown table format to improve tokenization.

• sliceHead, keep the top N rows

def("FILE", env.files, { sliceHead: 100 })

• sliceTail, keep the last N rows

def("FILE", env.files, { sliceTail: 100 })

• sliceSample, keep a random sample of N rows

def("FILE", env.files, { sliceSample: 100 })

Prompt Caching

You can specify ephemeral: true to enable prompt caching optimization. In particular, a def with ephemeral will be rendered at the back of the prompt to persist the cache prefix.

def("FILE", env.files, { ephemeral: true })

Safety: Prompt Injection detection

You can schedule a check for prompt injection/jai break with your configured content safety provider.

def("FILE", env.files, { detectPromptInjection: true })

Predicted output

Some models, like OpenAI gpt-4o and gpt-4o-mini, support specifying a predicted output (with some limitations). This helps reduce latency for model responses where much of the response is known ahead of time. This can be helpful when asking the LLM to edit specific files.

Set the prediction: true flag to enable it on a def call. Note that only a single file can be predicted.

def("FILE", env.files[0], { prediction: true })

Note

This feature disables line number insertion.

Data definition (defData)

The defData function offers additional formatting options for converting a data object into a textual representation. It supports rendering objects as YAML, JSON, or CSV (formatted as a Markdown table).

// render to markdown-ified CSV by default
defData("DATA", data)

// render as yaml
defData("DATA", csv, { format: "yaml" })

The defData function also supports functions to slice the input rows and columns.

• headers, list of column names to include
• sliceHead, number of rows to include from the beginning
• sliceTail, number of rows to include from the end
• sliceSample, number of rows to pick at random
• distinct, list of column names to deduplicate the data based on

defData("DATA", data, {
    sliceHead: 5,
    sliceTail: 5,
    sliceSample: 100,
})

You can leverage the data filtering functionality using parsers.tidyData as well.

Diff Definition (defDiff)

It is very common to compare two pieces of data and ask the LLM to analyze the differences. Using diffs is a great way to naturally compress the information since we only focus on differences!

The defDiff takes care of formatting the diff in a way that helps LLM reason. It behaves similarly to def and assigns a name to the diff.

// diff files
defDiff("DIFF", env.files[0], env.files[1])

// diff strings
defDiff("DIFF", "cat", "dog")

// diff objects
defDiff("DIFF", { name: "cat" }, { name: "dog" })

You can leverage the diff functionality using parsers.diff.