Computing with Crochet

Type and command declarations provide the structure for Crochet programs—they describe a model for the world. But how this world behaves is described with expressions. In this chapter we’ll dive deep into how these expressions work—how we make Crochet do things.

• Execution models
  • Immediate evaluation
    • Evaluation of sub-expressions
    • When does this matter?
  • Partial programs
    • Applications with multiple holes
    • Anonymous partial programs
    • Evaluation time in partial programs
  • Delayed programs
    • Regular delayed programs
    • Lazy delayed programs
• Naming values
  • Global Names
    • Syntactical restrictions
    • Why are they restricted?
    • Where can global names be used?
  • Local names
    • When are local names valid?
    • Reusing names in nested regions
    • When are names usable?
• Intrinsic data types
  • Gradual representations
    • The any type
    • The unknown type
      • A note on overwrapping
    • The sealed type
    • The nothing type
  • Numeric models
    • Approximating fractionals
    • Mixed operations
  • Textual models
    • Text literals
      • Unicode escapes
    • Text composition
      • Non-text composition
    • Text and trust
  • Logical models
  • Program representations
    • Thunks
    • Functions
      • Partials
  • Collections
    • Lists
    • Records
      • Security considerations
• Applying programs and commands
  • Application in a nutshell
    • Commands
    • Functions
    • Thunks
  • Precedence
    • A note on arithmetic convention
  • Associativity
  • Pipes
    • Functional pipes
• Using data
  • Literal data
  • The new operator
    • Constructing capabilities
  • Projecting fields
    • Non-existing fields
    • Fields and inheritance
    • Visibility of fields
  • Projection with non-typed data
    • Record projection
    • Sequence projection
• Equality
  • Intrinsic equality
  • Value identity
  • Custom equality
    • Security considerations
• Branching
  • Conditions
• Working with multiple values
  • The for .. in .. do .. syntax
    • Filtering items
    • Combining collections
    • Results of for syntaxes